#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define rep(i, n) for (int i = 0; i < (int)(n); ++i)
#define all(c) begin(c), end(c)
#define dump(x) cerr << __LINE__ << ":\t" #x " = " << (x) << endl

using LL = __int128;

LL MS = 1000000000000000003;
LL MT = 1000000000000000009;
LL s[1000010], t[1000010];
map<pair<LL,LL>, int> first;

int main(){
	cin.tie(0);
	ios::sync_with_stdio(0);
	int n, q;
	cin >> n >> q;
	s[0] = t[0] = 1;
	for(int i = 0; i < n; ++i) s[i+1] = s[i] * 114 % MS;
	for(int i = 0; i < n; ++i) t[i+1] = t[i] * 514 % MT;
	pair<LL,LL> cur(0, 0);
	first[cur] = 0;
	for(int i = 0; i < q; ++i){
		char c;
		cin >> c;
		if(c == '?'){
			cout << first[cur] << '\n';
		} else {
			int l, r, k;
			cin >> l >> r >> k;
			cur.first  += (s[r] - s[l] + MS) * (k + MS);
			cur.first  %= MS;
			cur.second += (t[r] - t[l] + MT) * (k + MT);
			cur.second %= MT;
			if(!first.count(cur)) first[cur] = i + 1;
		}
	}
}