#include <iostream>
#include <cstdio>
#include <map>

using namespace std;

const int N = 1000010;

int n, q, idx;
map<int, int> cf; // 存非零
map<string, int> mm;

string ToStr() {
    string ret = "";
    for (auto [pos, cnt] : cf) {
        if (cnt == 0) continue;
        ret += (pos + '0');
        ret += ',';
        if (cnt < 0) ret += '-';
        ret += (abs(cnt) + '0');
        ret += ';';
    }
    return ret;
}

int main() {
    // freopen("seq.in", "r", stdin);
    // freopen("seq.out", "w", stdout);

    scanf("%d%d", &n, &q);

    
    string ss = ToStr();
    if (!mm.count(ss)) mm[ss] = 0;
    for (int i = 1; i <= q; ++i) {
        char op;
        scanf(" %c", &op);
        if (op == '!') {
            int l, r, k;
            scanf("%d%d%d", &l, &r, &k);

            cf[l] += k, cf[r] -= k;
            while (cf.find(0) != cf.end()) cf.erase(cf.find(0));
            string s = ToStr();
            if (!mm.count(s)) mm[s] = i;
        } else {
            string s = ToStr();
            printf("%d\n", mm[s]);
        }
    }

    return 0;
}