def q(x):
    print('?', x)
    return input() == 'safe'

def ans(x):
    print('!', x)
    return

if not q(1):
    ans(0)
    exit()
l = 1
r = 1000
while r - l > 1:
    c = (r + l) // 2
    if q(c):
        l = c
    else:
        if q(c+1):
            l = c+1
        else:
            r = c
ans(l)