#include <iostream>
#include <vector>
#include <algorithm>
#include <cmath>
using namespace std;
using i32 = int32_t;
using u32 = uint32_t;
using i64 = int64_t;
using u64 = uint64_t;
#define rep(i,n) for(int i=0; i<(n); i++)

int main() {
    cout.precision(10);
    fixed(cout);
    double l = -6.0 * log(10);
    double r = log(12.22) + 74.0 * log(10);
    cout << exp(r) << endl;
    rep(t,24){
        double m = (l+r) / 2;
        double em = exp(m);
        cout << "? " << em << endl;
        string res; cin >> res;
        if(res == "-1") return 0;
        if(res == "Yes") r = m;
        else l = m;
    }
    double m = (l+r)/2;
    cout << "! " << exp(m) << endl;
    return 0;
}


struct ios_do_not_sync{
    ios_do_not_sync(){
        ios::sync_with_stdio(false);
        cin.tie(nullptr);
    }
} ios_do_not_sync_instance;