import sys
input = sys.stdin.readline

NG=10**3
OK=0

while NG-OK>4:
    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-1
        else:
            NG=mid-1

for i in range(NG,OK,-1):
    print("?",i,flush=True)
    if input().strip()=="safe":
        OK=i
        break
    

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