#pragma GCC target("avx")
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
#include<iostream>
using namespace std;
using i32 = int_fast32_t;
using i64 = int_fast64_t;
#define rep(i, n) for (i32 i = 0; i < (i32)(n); i++)
#define all(a) (a).begin(),(a).end()
#define rall(a) (a).rbegin(),(a).rend()
using P = pair<i64,i64>;
void binary_search(){
    i64 lb = 0,ub = 1e9 + 1;
    i64 mid;
    while(ub - lb > 1){
        mid = (ub + lb) / 2;
        cout << "?" << " " << mid << endl;
        string s;
        cin >> s;
        if(s == "out")ub = mid;
        else lb = mid;
    }
    cout << "! " << lb << endl;
    return;
}
int main(){
ios::sync_with_stdio(false);
std::cin.tie(nullptr);
binary_search();
}