import sys
def input(): return sys.stdin.readline().strip()
def mapint(): return map(int, input().split())
sys.setrecursionlimit(10**9)

s = set()
primes = []
for i in range(2, 1001):
    if i in s:
        continue
    primes.append(i)
    cnt = 2
    while cnt*i<1001:
        s.add(cnt*i)
        cnt += 1
leng = len(primes)
l, r = 0, leng
cnt = 0
while l+1<r:
    half = (l+r)//2
    print('? {}'.format(primes[half]))
    sys.stdout.flush()
    cnt += 1
    answer = input()
    if answer=='safe':
        l = half
    else:
        r = half

if l!=leng-1:
    right = primes[l+1]
else:
    right = 1000
for _ in range(cnt, 25):
    print('? {}'.format(right-1))
    sys.stdout.flush()
    if input()=='safe':
        break
    else:
        right -= 1
print('! {}'.format(right-1))
sys.stdout.flush()
exit()