#include <fstream>
#include <string>
#include <algorithm>
#include <iostream>
#define maxn 1000010
#define fin cin
#define fout cout
//typedef int long long;
using namespace std;
//ifstream fin("classrooms.in");
//ofstream fout("classrooms.out");
int n,m;
const int INF=1<<30;
int minv[maxn*4],data[maxn],addv[maxn*4];
int _min;
void mt(int o,int L,int R)
{
	int lc=o<<1,rc=(o<<1)+1;
	minv[o]=0;
	if(L<R)
	{
		minv[o]=min(minv[lc],minv[rc]);
	}
	minv[o]+=addv[o];
}
void build(int o,int L,int R)
{
	int lc=o<<1,rc=(o<<1)+1;
	if(L==R)addv[o]=data[L];
	else
	{
		int M=(L+R)>>1;
		build(lc,L,M);
		build(rc,M+1,R);
	}
	mt(o,L,R);
}
int ql,qr;
int v;
void update(int o,int L,int R)
{
	int lc=o<<1,rc=(o<<1)+1;
	if(ql<=L&&R<=qr)addv[o]+=v;
	else
	{
		int M=(L+R)>>1;
		if(ql<=M)update(lc,L,M);
		if(M<qr)update(rc,M+1,R);
	}
	mt(o,L,R);
}
void query(int o,int L,int R,int add)
{
	int lc=o<<1,rc=(o<<1)+1;
	if(ql<=L&&R<=qr)_min=min(minv[o]+add,_min);
	else
	{
		int M=(L+R)>>1;
		if(ql<=M)query(lc,L,M,add+addv[o]);
		if(M<qr)query(rc,M+1,R,add+addv[o]);
	}
}
int main()
{
	freopen("classrooms.in","r",stdin);
	freopen("classrooms.out","w",stdout);
	ios::sync_with_stdio(0);
	fin>>n>>m;
	for(int i=1;i<=n;++i)
		fin>>data[i];
	build(1,1,n);
	int d;
	for(int i=1;i<=m;++i)
	{
		fin>>d>>ql>>qr;
		_min=INF;
		query(1,1,n,0);
		if(_min>=d)
		{
			v=-d;
			update(1,1,n);
		}
		else
		{
			fout<<-1<<endl;
			fout<<i<<endl;
			return 0;
		}
	}
	fout<<0<<endl;
}