def solution(pegs):
    odd, even = sum_odd_even(pegs)

    if len(pegs) % 2 == 0:
        s = 2 * odd - 2 * even - pegs[-1] + pegs[0]
        if 2*s < 3:
            return [-1, -1]
        if s % 3 == 0:
            return [2*s/3, 1]
        else:
            return [2*s, 3]
    else:
        s = 2 * odd - 2 * even + pegs[-1] + pegs[0]
        if 2*s < 1:
            return [-1, -1]
        return [2*s, 1]

def sum_odd_even(pegs):
    odd, even = 0, 0
    for i, peg in enumerate(pegs):
        if i % 2 == 1:
            odd += peg
        else:
            even += peg
    return odd, even


tests = [
        ([4, 30, 50], [12, 1]),
        ([4, 17, 50], [-1, -1]),
        ([1, 2], [-1, -1]),
        ([1, 2, 3], [-1, -1]),
        ]

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