l = 0
h = 1000
while h-l>1:
    m = (l+h)//2
    print("?",m)
    x = input().strip()
    if x=="safe":
        l = m
    else:
        print("?",m+1)
        y = input().strip()
        if y=="safe":
            l = m+1
        else:
            h = m
print("!",l)