C++ :

#include<bits/stdc++.h>
using namespace std;
long long n,m,k,w,mid;
long long d[1000005],s[1000005],j[1000005],r[1000005];
long long cf[1000005],rr[1000005];
bool bz;
bool check(long long a)
{	
	/*cout<<"---"<<endl;
	cout<<a<<endl;*/
	memset(cf,0,sizeof(cf));
	for(int i=1;i<=a;++i)
	{
		cf[s[i]]+=d[i];
		cf[j[i]+1]-=d[i];
	}
	/*for(int i=1;i<=n;++i)
	{
		cout<<cf[i]<<" ";
	}
	cout<<endl;*/
	for(int i=1;i<=n;++i)
	{
		rr[i]=rr[i-1]+cf[i];
		//cout<<rr[i]<<" ";
		if(rr[i]>r[i]) return 0;
	}
	return 1;
}
int main(){
    cin>>n>>m;
    for(int i=1;i<=n;++i)
    {
    	scanf("%lld",&r[i]);
    }
    
    for(int i=1;i<=m;++i)
    {
    	scanf("%lld %lld %lld",&d[i],&s[i],&j[i]);
    	if(s[i]>j[i]) swap(s[i],j[i]);
    }
    k=0;w=n+1; 
    while(k+1<w)
    {
    	mid=(k+w)/2;
    	if (check(mid)) k=mid;
    		else w=mid;
    	/*cout<<k<<" "<<w<<endl;
    	cout<<"---"<<endl;*/
    }
    if(w==n+1) cout<<0;
		else cout<<-1<<endl<<w; 
    return 0;
}