#include<iostream>
#include<iomanip>
#include<math.h>
#include<algorithm>
#include<cstdio>
#include<cstring>
#include<string>
#include<queue>
#include<vector>
#include<set>
#include<stack>
#include<map>
#define maxn 2010000
#define mod 9901
using namespace std;
long long n, m,jiao[maxn],jiaocha[maxn],shu[maxn], st[maxn], et[maxn],zi[maxn],ans;
bool pa = false,spa;
int main()
{
    cin >> n >> m;
    for (int i = 1; i <= n; ++i) {
        cin >> jiao[i];
    }
    for (int i = 1; i <= m; ++i) {
        cin >> shu[i] >> st[i] >> et[i];
    }
    long long l = 1, r = m,mid;
    while (l <= r) {
        spa = false;
        memset(zi, 0, sizeof(zi));
        memset(jiaocha, 0, sizeof(jiaocha));
        mid = (l + r) >> 1;
        for (long long i = 1; i <= mid; ++i) {
            jiaocha[st[i]] += shu[i];
            jiaocha[et[i] + 1] -= shu[i];
        }
        for (long long i = 1; i <= n; ++i) {
            zi[i] = zi[i - 1] + jiaocha[i];
            //cout << zi[i] <<" ";
        }
        //cout << endl;
        for (long long i = 1; i <= n; ++i) {
            if (zi[i] > jiao[i]) {
                pa = true;
                spa = true;
                ans =mid;
                break;
            }
        }
        if (spa) {
            r = mid-1;
        }
        else {
        l = mid+1;
        }
    }
    if (pa) {
        cout << -1<<endl<<ans;
        return 0;
    }
    cout << 0;
    return 0;
}
inline int read() {
    int w = 1, q = 0;
    char ch = ' ';
    while (ch != '-' && (ch < '0' || ch > '9')) ch = getchar();
    if (ch == '-') w = -1, ch = getchar();
    while (ch >= '0' && ch <= '9') q = q * 10 + ch - '0', ch = getchar();
    return w * q;
}