#include<bits/stdc++.h>
using namespace std;

typedef long long ll;
const int N = 1e6 + 10;

ll n,m;
ll r[N],d[N],s[N],t[N],cnt[N],need[N];

bool check(int x){
    memset(cnt,0,sizeof(cnt));
    for(int i = 1;i <= x;i++){
        cnt[s[i]] += d[i];
        cnt[t[i] + 1] -= d[i];
    }
    for(int i = 1;i <= n;i++){
        need[i] = need[i - 1] + cnt[i];
        if(need[i] > r[i]) return false;
    }
    return true;
}

int main(){
    ios::sync_with_stdio(false);
    cin.tie(0);cout.tie(0);

    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] >> t[i];

    ll l = 0,r = m - 1,mid;
    while(l < r){
        mid = l + r + 1 >> 1;
        if(check(mid)) l = mid;
        else r = mid - 1;
    }

    if(l == m - 1){
        cout << "0" << endl;
    }else{
        cout << "-1" << endl << mid << endl;
    }
    
    return 0;
}