#include<bits/stdc++.h>
#define int long long
using namespace std;
int x,n,ans;
struct chocolate{
	int a,b,c;
}g[100005];
bool cmp(chocolate a,chocolate b){
	if(a.a!=b.a)
		return a.a<b.a;
	return a.b<b.c;
}
signed main(){
	ios::sync_with_stdio(false);
	cin.tie(0),cout.tie(0);
	cin>>x>>n;
	for(int i=1;i<=n;i++){
		cin>>g[i].a>>g[i].b>>g[i].c;
	}
	sort(g+1,g+n+1,cmp);
	int l=0;
	for(int i=1;i<=n;i++){
		if(x==0)break;
		ans+=min(x,min(max(g[i].b-l,1ll*0),g[i].c))*g[i].a;
		l+=min(x,min(max(g[i].b-l,1ll*0),g[i].c));
		x-=min(x,min(max(g[i].b-l,1ll*0),g[i].c));
		
	}
	cout<<ans;
}