int left=,right=m;

    while(left<right)//二分

    {

        int mid=(left+right)>>;

        if(check(mid)) left=mid+;

        else right=mid;

    }

bool check(int x)//差分,判断

{

    memset(f,,sizeof(f));

    for(int i=;i<=x;i++)

    {

        f[l[i]]+=d[i];

        f[r[i]+]-=d[i];

    }

    for(int i=;i<=n;i++)

    {

        g[i]=g[i-]+f[i];

        if(a[i]<g[i])

        return ;

    }

    return ;

}

#include<iostream>

#include<stdio.h>

#include<math.h>

#include<string.h>

#include<stdlib.h>

#include<algorithm>

using namespace std;

const int maxn=1e6+;

int a[maxn],l[maxn],r[maxn],d[maxn],f[maxn],g[maxn],n,m;

bool check(int x)//差分,判断

{

    memset(f,,sizeof(f));

    for(int i=;i<=x;i++)

    {

        f[l[i]]+=d[i];

        f[r[i]+]-=d[i];

    }

    for(int i=;i<=n;i++)

    {

        g[i]=g[i-]+f[i];

        if(a[i]<g[i])

        return ;

    }

    return ;

}

signed main()

{

    ios::sync_with_stdio(false),cin.tie(),cout.tie();

    cin>>n>>m;

    for(int i=;i<=n;i++)

        cin>>a[i];

    for(int i=;i<=m;i++)

        cin>>d[i]>>l[i]>>r[i];

    if(check(n))

    {

        cout<<"";

        return ;

    }

    else cout<<"-1"<<endl;

      int left=,right=m;

    while(left<right)//二分

    {

        int mid=(left+right)>>;

        if(check(mid)) left=mid+;

        else right=mid;

    }

    cout<<left;

    return ;

}