#include<bits/stdc++.h>
#define int long long
using namespace std;
const int N=100010;
struct node
{
    int val,time,cnt;
}a[N];
set<int> s;
bool cmp(node a,node b)
{
    if(a.val!=b.val) return a.val<b.val;
    else return a.time>b.time;
}
int x,n;
signed main()
{
    cin>>x>>n;
    for(int i=1;i<=n;i++) cin>>a[i].val>>a[i].time>>a[i].cnt;
    for(int i=1;i<=x;i++) s.insert(i);
    int res=0;
    int p=1;
    sort(a+1,a+n+1,cmp);
    while(s.size()&&p<=n)
    {
        while(s.size()&&a[p].cnt&&*s.begin()<=a[p].time)
        {
            res+=a[p].val;
            auto t=s.upper_bound(a[p].time);
            t--;
            s.erase(t);
            a[p].cnt--;
        }
        p++;
    }
    if(s.size()) cout<<-1<<endl;
    else cout<<res<<endl;
    return 0;
}