def main():
    # fin = open('input.txt', 'r')
    # fout = open('output.txt', 'w')
    print('Hello world!')


if __name__ == "__main__":
    main()

# print('anything', file = fout) -> write anything to output.txt with '\n', print('anything', file = fout, end = '') without '\n'
# fin.realine() -> get string from input.txt
# fin.readline().split() -> get array of strings divided by space: 'ha   ha  h' -> ['ha', 'ha', 'h']
# map(int, fin.readline().split()) -> get array of number from string: '123123       3 321     1 12 ' -> [123123, 3, 321, 1, 12]
# fin, fout is fin = open('input.txt', 'r') and fout = open('output.txt', 'w')
# n, k = map(int, input.split()) get n, k from console
