#include<bits/stdc++.h>
#include<string.h>
#include <algorithm>
#include <iterator>
#include <set>
#include <stdlib.h>
#define ll long long
#define fr first
#define sc second
#define pb push_back
using namespace std;
ll a,b,c,d,e,f,m,i,j,n,h,g,l,r,ka,p,q[200005];
map<ll,ll> see;
map<ll,ll> mii,mee,maa;
pair<double,ll> t[400005];
vector<ll> vas[106],ves[205],vis,vii;
string x,y[1000],z;
pair<ll,ll> wefe,k[200005];
priority_queue<ll> pq;
stack<ll> munkh;
set<ll> st;
int main(){
cin>>a>>b;
for(i=0 ; i<b ; i++){
cin>>k[i].first>>k[i].second>>q[i];
t[i].first=k[i].first/k[i].second;
t[i].second=i;
}
sort(t,t+b);
g=0;
for(i=b-1 ; i>=0 ; i--){
h=a/k[t[i].second].second;
h=min(h,q[t[i].second]);
a=a-h;
h*=k[t[i].second].first;
g+=h;
}
cout<<g<<endl;
}
