#include <cstdio>
#include <cstring>
#include <iostream>
#include <string>
#include <cmath>
#include <bitset>
#include <vector>
#include <map>
#include <set>
#include <queue>
#include <deque>
#include <algorithm>
#include <complex>
#include <unordered_map>
#include <unordered_set>
#include <random>
#include <cassert>
#include <fstream>
#define popcount __builtin_popcount
using namespace std;
typedef long long int ll;
typedef pair<int, int> P;
ll mod[3]={1000000007, 1000000009, 998244353};
ll b0[2]={314159265, 358979323};
ll powmod(ll a, ll k, ll MOD){
    ll ap=a, ans=1;
    while(k){
        if(k&1){
            ans*=ap;
            ans%=MOD;
        }
        ap=ap*ap;
        ap%=MOD;
        k>>=1;
    }
    return ans;
}
ll inv(ll a, ll MOD){
	return powmod(a, MOD-2, MOD);
}
int n;
ll p[1000010];
int main()
{
    int q; cin>>n>>q;
    char c[100010];
    ll l[100010], r[100010], k[100010];
    for(int i=1; i<=q; i++){
        cin>>c[i];
        if(c[i]=='!') cin>>l[i]>>r[i]>>k[i];
    }
    int ans[100010]={};
    for(int t=0; t<6; t++){
        ll b=b0[t%2], MOD=mod[t%3];
        ll bv=inv(b-1, MOD);
        p[0]=1;
        for(int i=1; i<n; i++) p[i]=p[i-1]*b%MOD;
        ll s=0;
        map<ll, int> mp;
        mp[0]=0;
        for(int i=1; i<=q; i++){
            if(c[i]=='!'){
                (s+=(k[i]+MOD)*(p[r[i]]-p[l[i]]+MOD)%MOD*bv)%=MOD;
                if(mp.find(s)==mp.end()){
                    mp[s]=i;
                }
            }else{
                ans[i]=max(ans[i], mp[s]);
            }
        }
    }
    for(int i=1; i<=q; i++){
        if(c[i]=='?') cout<<ans[i]<<endl;
    }
    return 0;
}