import sys
input = sys.stdin.readline

NG=10**3
OK=-1

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

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

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

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