#include<iostream>
#include<cstring>
using namespace std;
typedef long long LL;
const int N = 1e6 + 10;
LL a[N], d[N], s[N], t[N], b[N];
int n, m;
bool check(int u)
{
    memset(b, 0, sizeof(b));
    for (int i = 1; i <= u; ++ i)
    {
        b[s[i]] += d[i];
        b[t[i] + 1] -= d[i];
    }
    for (int i = 1; i <= n; ++ i)
    {
        b[i] += b[i - 1];
        if (b[i] > a[i]) return false;
    }
    return true;
}
int main()
{
    cin >> n >> m;
    for (int i = 1; i <= n; ++ i) scanf("%d", &a[i]);
    for (int i = 1; i <= m; ++ i) scanf("%d%d%d", &d[i], &s[i], &t[i]);

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