Input: Read this: Due to reciprocity (discussed above) the gain of an antenna used for transmitting must be proportional to its effective area when used for receiving. Consider an antenna with no loss, that is, one whose electrical efficiency is 100%. It can be shown that its effective area averaged over all directions must be equal to λ2/4π, the wavelength squared divided by 4π. Gain is defined such that the average gain over all directions for an antenna with 100% electrical efficiency is equal to 1. Therefore, the effective area Aeff in terms of the gain G in a given direction is given by:
Question: What must the relationship of an antenna and the receiving area be due to reciprocity?

Output: proportional


Input: Read this: The sky is usually clear above the desert and the sunshine duration is extremely high everywhere in the Sahara. Most of the desert enjoys more than 3,600 h of bright sunshine annually or over 82% of the time and a wide area in the eastern part experiences in excess of 4,000 h of bright sunshine a year or over 91% of the time, and the highest values are very close to the theoretical maximum value. A value of 4,300 h or 98% of the time would be recorded in Upper Egypt (Aswan, Luxor) and in the Nubian Desert (Wadi Halfa). The annual average direct solar irradiation is around 2,800 kWh/(m2 year) in the Great Desert. The Sahara has a huge potential for solar energy production. The constantly high position of the sun, the extremely low relative humidity, the lack of vegetation and rainfall make the Great Desert the hottest continuously large area worldwide and certainly the hottest place on Earth during summertime in some spots. The average high temperature exceeds 38 °C (100.4 °F) - 40 °C (104 °F) during the hottest month nearly everywhere in the desert except at very high mountainous areas. The highest officially recorded average high temperature was 47 °C (116.6 °F) in a remote desert town in the Algerian Desert called Bou Bernous with an elevation of 378 meters above sea level. It's the world's highest recorded average high temperature and only Death Valley, California rivals it. Other hot spots in Algeria such as Adrar, Timimoun, In Salah, Ouallene, Aoulef, Reggane with an elevation between 200 and 400 meters above sea level get slightly lower summer average highs around 46 °C (114.8 °F) during the hottest months of the year. Salah, well known in Algeria for its extreme heat, has an average high temperature of 43.8 °C (110.8 °F), 46.4 °C (115.5 °F), 45.5 (113.9 °F). Furthermore, 41.9 °C (107.4 °F) in June, July, August and September. In fact, there are even hotter spots in the Sahara, but they are located in extremely remote areas, especially in the Azalai, lying in northern Mali. The major part of the desert experiences around 3 – 5 months when the average high strictly exceeds 40 °C (104 °F). The southern central part of the desert experiences up to 6 – 7 months when the average high temperature strictly exceeds 40 °C (104 °F) which shows the constancy and the length of the really hot season in the Sahara. Some examples of this are Bilma, Niger and Faya-Largeau, Chad. The annual average daily temperature exceeds 20 °C (68 °F) everywhere and can approach 30 °C (86 °F) in the hottest regions year-round. However, most of the desert has a value in excess of 25 °C (77 °F). The sand and ground temperatures are even more extreme. During daytime, the sand temperature is extremely high as it can easily reach 80 °C (176 °F) or more. A sand temperature of 83.5 °C (182.3 °F) has been recorded in Port Sudan. Ground temperatures of 72 °C (161.6 °F) have been recorded in the Adrar of Mauritania and a value of 75 °C (167 °F) has been measured in Borkou, northern Chad. Due to lack of cloud cover and very low humidity, the desert usually features high diurnal temperature variations between days and nights. However, it's a myth that the nights are cold after extremely hot days in the Sahara. The average diurnal temperature range is typically between 13 °C (55.4 °F) and 20 °C (68 °F). The lowest values are found along the coastal regions due to high humidity and are often even lower than 10 °C (50 °F), while the highest values are found in inland desert areas where the humidity is the lowest, mainly in the southern Sahara. Still, it's true that winter nights can be cold as it can drop to the freezing point and even below, especially in high-elevation areas.
Question: What is the lowest temperature recorded in the Sahara?

Output: unanswerable


Input: Read this: In 1924, the Tajik Autonomous Soviet Socialist Republic was created as a part of Uzbekistan, but in 1929 the Tajik Soviet Socialist Republic (Tajik SSR) was made a separate constituent republic, however the predominantly ethnic Tajik cities of Samarkand and Bukhara remained in the Uzbek SSR. Between 1927 and 1934, collectivization of agriculture and a rapid expansion of cotton production took place, especially in the southern region. Soviet collectivization policy brought violence against peasants and forced resettlement occurred throughout Tajikistan. Consequently, some peasants fought collectivization and revived the Basmachi movement. Some small scale industrial development also occurred during this time along with the expansion of irrigation infrastructure.
Question: Between 1917 and what year did collectivization of agriculture occur?

Output: unanswerable


Input: Read this: Chain department stores grew rapidly after 1920, and provided competition for the downtown upscale department stores, as well as local department stores in small cities. J. C. Penney had four stores in 1908, 312 in 1920, and 1452 in 1930. Sears, Roebuck & Company, a giant mail-order house, opened its first eight retail stores in 1925, and operated 338 by 1930, and 595 by 1940. The chains reached a middle-class audience, that was more interested in value than in upscale fashions. Sears was a pioneer in creating department stores that catered to men as well as women, especially with lines of hardware and building materials. It deemphasized the latest fashions in favor of practicality and durability, and allowed customers to select goods without the aid of a clerk. Its stores were oriented to motorists – set apart from existing business districts amid residential areas occupied by their target audience; had ample, free, off-street parking; and communicated a clear corporate identity. In the 1930s, the company designed fully air-conditioned, "windowless" stores whose layout was driven wholly by merchandising concerns.
Question: How many stores wasn't J. C. Penny operating in 1930?

Output:
unanswerable