def query(x: int) -> bool: print(f'? {x}') s = input() return s == 'safe' lo = 0 hi = 1000 ans = 0 while lo <= hi: m = (lo + hi) // 2 a = query(m) b = query(m+1) if a and b: ans = max(ans, m+1) lo = m + 2 elif a: ans = max(ans, m) lo = m + 1 elif b: ans = max(ans, m+1) lo = m + 2 else: hi = m - 1 print(f'! {ans}')