#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
using namespace std;
typedef long long ll;
using namespace __gnu_pbds;
#define endl '\n'
#define hitaf ios_base::sync_with_stdio(false); cin.tie(0);
#define fi first
#define se second
template <typename T>
using ordered_set = tree<T,null_type,less<T>,rb_tree_tag, tree_order_statistics_node_update>;
const ll MOD1 = 1e9 + 7;
const ll MOD = 998244353;
const ll INF = 4500000000000000000LL;
const ll mod1 = 6900000469;
const ll mod2 = 698000002369;
const int block = 447;
ll n, m, k, q, a[1200005], b[500005], c[500005];
string s, s1, s2;
bool dp[200005];
int main(){
hitaf
int T = 1;
// cin >> T;
while(T--){
cin >> m >> n;
for(int i = 1; i <= n; i++) cin >> a[i] >> b[i] >> c[i];
vector<ll> ord(n + 1);
iota(ord.begin(), ord.end(), 0);
sort(ord.begin() + 1, ord.end(), [&](ll x, ll y){
return a[x] * b[y] > a[y] * b[x];
});
ll ans = 0;
for(int i = 1; i <= n; i++){
ll idx = ord[i];
ll tmp = min(m / b[idx], c[idx]);
ans += a[idx] * tmp;
m -= tmp * b[idx];
}
cout << ans << endl;
}
}
