#include<bits/stdc++.h>
using namespace std;
#define rep(i,a,b) for(int i=a;i<b;i++)


typedef long long ll;
static const ll mo0 = 1000000007, mo1 = 1000000009;
static const ll add0 = 10009, add1 = 10007;
typedef pair<int, int> Hash;
int N, Q;
//-----------------------------------------------------------------
Hash imos[1010101];
void pre() {
	imos[0] = { 0, 0 };
	rep(i, 1, 1010101) imos[i + 1] = {(imos[i].first * add0 + add0) % mo0, (imos[i].second * add1 + add1) % mo1 };
}
Hash calc(Hash h, int L, int R, int K) {
	Hash one = imos[R];
	if (0 < L) one = { one.first - imos[L].first, one.second - imos[L].second };
	one.first = (one.first + mo0) % mo0;
	one.second = (one.second + mo1) % mo1;

	return{ (h.first + one.first * ((K + mo0) % mo0)) % mo0, (h.second + one.second * ((K + mo1) % mo1)) % mo1 };
}
//-----------------------------------------------------------------
map<Hash, int> ans;
int main() {
	cin.tie(0);
	ios::sync_with_stdio(false);
	cin >> N >> Q;
	pre();

	Hash h = { 0, 0 };
	ans[h] = 0;

	rep(q, 1, Q + 1) {
		char t; cin >> t;
		if (t == '!') {
			int L, R, K; cin >> L >> R >> K;
			h = calc(h, L, R, K);
			if (ans.count(h) == 0) ans[h] = q;
		} else {
			printf("%d\n", ans[h]);
		}
	}
}