import sys
iter = 1
ok = 0
ng = 1000
while iter <= 24:
    mid = (ok+ng)//2
    print ("? {}".format(mid))
    sys.stdout.flush()
    iter += 1
    res = input()
    if(res == 'safe'):
        ok = mid
        continue

    print ("? {}".format(mid+1))
    sys.stdout.flush()
    iter += 1
    res = input()
    if(res=='safe'):
        ok = mid+1
    else:
        ng = mid

print("! {}".format(ok))
sys.stdout.flush()