l = 0
r = 10 ** 3

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

while r - l > 1:
    mid = (l + r) // 2
    x = ask(mid)
    if x == "safe":
        l = mid
    else:
        x = ask(mid + 1)
        if x == "safe":
            l = mid + 1
        else:
            r = mid
    

print(f"! {l}")