a, b, c = list(map(int, input().split()))
l = 1
r = 10**9+1
while r - l > 1:
    m = (l + r) >> 1
    print("?", m-1, 1)
    a = int(input())
    if a < m-1:
        r = m
    else:
        l = m

l = 10
B = l
b = b**c
a0 = a
ans = 1
while b:
    if b & 1:
        ans = ans * a0 % B
    b >>= 1
    a0 = a0 * a0 % B
print("!", ans)