import sys

yes = 0
no = 10 ** 3
while no - yes > 1:
    mid = (yes + no)//2
    print("?", mid + 1)
    sys.stdout.flush()
    s = input()
    if s == "safe":
        yes = mid + 1
        continue
    print("?", mid)
    sys.stdout.flush()
    s = input()
    if s == "safe":
        yes = mid
    else:
        no = mid
        
print("!", yes)
sys.stdout.flush()