def solution(x, y):
    return str(((x + y - 1) * (x + y) / 2) - (y - 1))

tests = [
        ([1, 1], "1"),
        ([3, 2], "9"),
        ([5, 10], "96"),
        ([2, 3], "8")
        ]

for i, o in tests:
    result = solution(*i)
    print (i, result == o, result, o)