#N, D = 40, 5

def return_inp(x):
    if x>=N or x%D==0:
        return 'out'
    else:
        return 'safe'
        
def judge(m):
    #res1 = return_inp(m)
    print('?', m)
    res1 = input()
    #res2 = return_inp(m+1)
    print('?', m+1)
    res2 = input()
    return res1=='out' and res2=='out'
    
l, r = 1, 10**3+100
    
while l<=r:
    m = (l+r)//2
        
    if judge(m):
        r = m-1
    else:
        l = m+1

print('!', l-1)