l = 0
r = 1001
while r - l > 1:
    m = (l + r) // 2
    print("? {}".format(m))
    s = input()
    if s == "safe":
        l = m
        continue
    print("? {}".format(m + 1))
    s = input()
    if s == "safe":
        l = m + 1
    else:
        r = m

while r >= 0:
    print("? {}".format(r))
    if input() == "safe":
        break
    r -= 1
print("! {}".format(r))