/*
ID: apkessl1
PROG: feed
LANG: C++
*/
#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <algorithm>
#include <vector>
using namespace std;

FILE *fin = fopen ("feed.in", "r"), *fout = fopen ("feed.out", "w");

const int MAXN = 505;
const long long INFTY = (1LL << 60);
typedef long long ll;

int N, K;
ll E, X [MAXN], feed [MAXN], price [MAXN], best, p, total = 0;

int main ()
{
    fscanf (fin, "%d %lld %d", &K, &E, &N);

    for (int i = 0; i < N; i++)
        fscanf (fin, "%lld %lld %lld", X + i, feed + i, price + i), X [i] = E - X [i];

    for (int k = 1; k <= K; k++)
    {
        best = INFTY; p = 0;

        for (int i = 0; i < N; i++)
            if (feed [i] && price [i] + X [i] < best)
                best = price [i] + X [i], p = i;

        total += best; feed [p]--;

        for (int i = 0; i < N; i++)
            price [i] += (X [p] > X [i]) ? 2 * X [i] : 2 * X [p];
    }

    fprintf (fout, "%lld\n", total);
    return 0;
}