#include <iostream>
#include <vector>
#include <algorithm>
#include <cmath>
using namespace std;

int main() {
    cout.precision(15);
    fixed(cout);
    int T; cin >> T;
    double maxval = 1.222e75;
    vector<double> table;
    for(double i=0.0; i<1.0; i+=1.99e-5) table.push_back(i);
    table.push_back(1.0);
    while(table.back() < maxval) table.push_back(table.back() * (1.0 + 1.99e-5));
    table.back() = maxval;
    while(T--){
        int ok = 0;
        int ng = table.size() - 1;
        while(abs(ok - ng) > 1){
            int mid = (ok + ng) / 2;
            cout << "? " << table[mid] << endl;
            string res; cin >> res;
            if(res == "-1") return 0;
            if(res == "Yes") ok = mid; else ng = mid;
        }
        double ans = (table[ok] + table[ng]) / 2;
        cout << "! " << ans << endl;
    }
    return 0;
}