Задачи
Gauß in Elementary School
Gauß in Elementary School
Johann Carl Friedrich Gauß(1777-1855) was one of the most important German mathematicians . For those of you who remember the Deutsche Mark, a picture of him was printed on the 10,-DM bill. In elementary school, his teacher J. G. Buttner tried to occupy the pupils by making them add up the integers from \textbf{1} to \textbf{100}. The young Gauß surprised everybody by producing the correct answers (\textbf{5050}) within seconds.
Can you write a computer program that can compute such sums really quickly?
Given two integers n and m, you should compute the sum of all the integers from n to m. In other words, you should compute
\includegraphics{https://static.e-olymp.com/content/8b/8b5fb52099b766bad3d08de756f1bc4909844cb5.jpg}
i = n + (n + 1) + (n + 2) + ... + (m - 1) + m
\InputFile
The first line contains the number of scenarios. Each scenario consists of a line containing the numbers \textbf{n} and \textbf{m} (\textbf{-10^9} ≤ \textbf{n} ≤ \textbf{m }≤ \textbf{10^9}).
\OutputFile
The output for every scenario begins with a line containing "\textbf{Scenario #i:}", where \textbf{i} is the number of the scenario starting at \textbf{1}. Then print the sum of all integers from \textbf{n} to \textbf{m}. Terminate the output for the scenario with a blank line.
Входные данные #1
3 1 100 -11 10 -89173 938749341
Выходные данные #1
Scenario #1: 5050 Scenario #2: -11 Scenario #3: 440625159107385260