#include <bits/stdc++.h>


using namespace std;
typedef long long ll;

#define REP(i,n) for(int i=0; i<int(n); i++)
#define FOR(i,m,n) for(int i=int(m); i<int(n); i++)
#define ALL(obj) (obj).begin(),(obj).end()
#define VI vector<int>
#define VP vector<pair<int,int>>
#define VPP vector<pair<int,pair<int,int>>>
#define VLL vector<long long>
#define VVI vector<vector<int>>
#define VVLL vector<vector<long long>>
#define VC vector<char>
#define VS vector<string>
#define VVC vector<vector<char>>
#define VB vector<bool>
#define VVB vector<vector<bool>>
#define fore(i,a) for(auto &i:a)
typedef pair <int, int> P;
template<typename T> using min_priority_queue = priority_queue<T, vector<T>, greater<T>>;
template<class T> bool chmax(T &a, T b) { if (a < b) { a = b; return true; } return false; }
template<class T> bool chmin(T &a, T b) { if (a > b) { a = b; return true; } return false; }

const int  INF = 1 << 29;
const ll INFL = 1LL << 60;
const ll mod = 998244353;

const int MAX = 1010000;
long long fac[MAX], finv[MAX], inv[MAX];

void COMinit() {
	fac[0] = fac[1] = 1;
	finv[0] = finv[1] = 1;
	inv[1] = 1;
	for (int i = 2; i < MAX; i++) {
		fac[i] = fac[i - 1] * i % mod;
		inv[i] = mod - inv[mod%i] * (mod / i) % mod;
		finv[i] = finv[i - 1] * inv[i] % mod;
	}
}

long long COM(int n, int k) {
	if (n < k) return 0;
	if (n < 0 || k < 0) return 0;
	return fac[n] * (finv[k] * finv[n - k] % mod) % mod;
}

long long modinv(long long a, long long m) {
	long long b = m, u = 1, v = 0;
	while (b) {
		long long t = a / b;
		a -= t * b; swap(a, b);
		u -= t * v; swap(u, v);
	}
	u %= m;
	if (u < 0) u += m;
	return u;
}


int main(){

	int ok = 1001;
	int ng = -1;

	while (ok - ng > 1) {
		int mid = (ok + ng) / 2;
		string s;
		cout << "? " << mid << endl;
		cin >> s;
		if (s == "safe") {
			ng = mid;
			continue;
		}

		cout << "? " << mid + 1 << endl;
		cin >> s;
		if (s == "safe") {
			ng = mid + 1;
		}
		else {
			ok = mid;
		}
	}
	cout << ng << endl;
}