#include <bits/stdc++.h>
using namespace std;
#define int long long
bool cmp(array<int, 3>&a, array<int, 3>&b) {
if (a[0] * b[1] > a[1] * b[0]) {
return true;
}
else if (a[0] * b[1] == a[1] * b[0]) {
return a[0] <= b[0];
}
else return false;
}
signed main() {
int s, n; cin >> s >> n; vector<array<int, 3>> A;
for (int i = 0; i < n; i++) {
int u, v, w; cin >> u >> v >> w;
A.push_back({u, v, w});
}
sort(A.begin(), A.end(), cmp); int sum = 0;
for (int i = 0; i < n; i++) {
// cout << A[i][0] << " " << A[i][1] << " " << A[i][2] << "\n";
int x = s / A[i][1];
x = min(x, A[i][2]);
sum += A[i][0] * x; s -= A[i][1] * x;
}
cout << sum;
}
