// #includes {{{
#include <algorithm>
#include <numeric>
#include <iostream>
#include <string>
#include <vector>
#include <queue>
#include <list>
#include <deque>
#include <stack>
#include <set>
#include <map>
#include <cstdio>
#include <cstdlib>
#include <cassert>
#include <cstring>
#include <cmath>
using namespace std;
// }}}
// pre-written code {{{
#define REP(i,n) for(int i=0;i<(int)(n);++i)
#define RREP(i,a,b) for(int i=(int)(a);i<(int)(b);++i)
#define FOR(i,c) for(__typeof((c).begin()) i=(c).begin();i!=(c).end();++i)
#define LET(x,a) __typeof(a) x(a)
//#define IFOR(i,it,c) for(__typeof((c).begin())it=(c).begin();it!=(c).end();++it,++i)
#define ALL(c) (c).begin(), (c).end()
#define MP make_pair

#define EXIST(e,s) ((s).find(e)!=(s).end())

#define RESET(a) memset((a),0,sizeof(a))
#define SET(a) memset((a),-1,sizeof(a))
#define PB push_back
#define DEC(it,command) __typeof(command) it=command

//debug
#define dump(x)  cerr << #x << " = " << (x) << endl;
#define debug(x) cerr << #x << " = " << (x) << " (L" << __LINE__ << ")" << " " << __FILE__ << endl;
#define debug2(x) cerr << #x << " = [";REP(__ind,(x).size()){cerr << (x)[__ind] << ", ";}cerr << "] (L" << __LINE__ << ")" << endl;

const int INF=0x3f3f3f3f;

typedef long long Int;
typedef unsigned long long uInt;
#ifdef __MINGW32__
typedef double rn;
#else
typedef long double rn;
#endif

typedef pair<int,int> pii;

/*
#ifdef MYDEBUG
#include"debug.h"
#include"print.h"
#endif
*/
// }}}

const int D = 1000010;
const uInt P = 1000000009ull;

int N,Q;

uInt pm[D],hsum[D];

int main(){
	cin>>N>>Q;
	uInt h = 0ull, pw = 1ull;
	for(int i=0;i<=N;i++){
		hsum[i] = h;
		pm[i] = pw;
		h*=P;
		h+=1ull;
		pw*=P;
	}
	map<uInt,int> mp;
	h = 0ull;
	mp[h] = 0;
	REP(i,Q){
		char c;
		cin>>c;
		if(c=='!'){
			int L,R,K;
			cin>>L>>R>>K;
//			cerr<<L<<" "<<R<<" "<<K<<endl;
			h+=pm[L]*hsum[R-L]*((uInt)K);
			/*
			dump(pm[L]);
			dump(hsum[R-L]);
			dump((uInt)K)
			*/
//			cerr<<i+1<<" "<<h<<endl;
			if(mp.find(h)==mp.end())mp[h] = i+1;
		}else{
//			cerr<<h<<endl;
			cout<<mp[h]<<endl;
		}
	}
	return 0;
}