def question(x):
    print(f"? {x}", flush=True)
    return input() == 'safe'


l, r = 0, 1000
while (r - l) > 1:
    m = (r + l) // 2
    if question(m):
        l = m
    elif question(m + 1):
        l = m + 1
    else:
        r = m
print(f"! {l}")