#include<bits/stdc++.h>
#include<iostream>
#include<cstdio>
#include<cmath>
#include<algorithm>
#include<cstring>
#include<string>
#include<sstream>
using namespace std;
const int N=1000000+10;
int r[N],d[N],s[N],j[N],t[N],q[N];
int n,m;
bool check(int x){
	memset(t,0,sizeof(t));
	for(int i=1;i<=x;i++){//差分 
		t[s[i]]+=d[i];
		t[j[i]+1]-=d[i];
	}
	for(int i=1;i<=n;i++){//每天需要的教室数量 
		q[i]=q[i-1]+t[i];
		if(q[i]>r[i])return true;
	}
	return false;
}
int main (){
	cin>>n>>m;
	for(int i=1;i<=n;i++){
		cin>>r[i];
	}
	for(int i=1;i<=m;i++){
		cin>>d[i]>>s[i]>>j[i];
	}
	if(!check(m)){
		cout<<0;
		return 0;
	}
	int l=1,r=m;
	while(l<r){
		int mid=(l+r)/2;
		if(check(mid))r=mid;
		else l=mid+1;
	}
	cout<<-1<<endl<<l; 
 	return 0;
}