m = 10**9 + 7
a, b, k, c = tuple(int(x) for x in input().split())


def solve(x):
    res = 1
    while x != 1:
        res = (res * 2) % m
        x -= 1
    print(res * k % m)

if k == 0:
    print(0)
elif a == b and b == c:
    print(k)
elif a != c and b != c:
    print(0)
else:
    solve(k)