#include<bits/stdc++.h>
#include<bits/extc++.h>
#define int long long
#define inf 0x3f3f3f3f3f3f3f3f
#define maxn 1234567
#define eps 1e-7
#define mod 1000000007
#define Mod 998244353
#define f(i,a,b) for(int i=a;i<=b;i++)
#define r(i,a,b) for(int i=a;i>=b;i--) 
#define fx(i,a,b,x) for(int i=a;i<=b;i+=x)
#define rx(i,a,b,x) for(int i=a;i>=b;i-=x) 
#define base 19260817
using namespace std;
using namespace __gnu_cxx;
using namespace __gnu_pbds;
int T;
int n,q,Hash[maxn]={1},x,L,R,k;
map<int,int>mp;
char op;
void solve(){
	scanf("%lld%lld",&n,&q);
	f(i,1,n)Hash[i]=Hash[i-1]*base;
	f(i,1,q){
		cin>>op;
		if(op=='!'){
			scanf("%lld%lld%lld",&L,&R,&k);
			x+=k*(Hash[R]-Hash[L]);
		}
		else printf("%lld\n",mp[x]);
		if(mp.count(x)==0)mp[x]=i;
	}
}
signed main(){
	T=1;
//	scanf("%lld",&T);
	while(T--)solve();
	return 0;
}