import sys
input = sys.stdin.readline

OK=10**3
NG=-1

while OK-NG>1:
    mid=(OK+NG)//2
    print("?",mid,flush=True)

    if input().strip()=="safe":
        NG=mid-1
    else:
        print("?",mid+1,flush=True)

        if input().strip()=="safe":
            NG=mid
        else:
            OK=mid-1

print("!",OK,flush=True)