#include<bits/stdc++.h>

using namespace std;

const int INF = 1 << 30;

void chmin(int &a, int b)
{
  a = min(a, b);
}

int main()
{
  int Gx, Gy, N, F;
  int x[50], y[50], z[50];

  cin >> Gx >> Gy >> N >> F;
  for(int i = 0; i < N; i++) {
    cin >> x[i] >> y[i] >> z[i];
  }

  int dp[203][203];
  fill_n(*dp, 203 * 203, INF);
  dp[0][0] = 0;
  for(int i = 0; i <= Gx; i++) {
    for(int j = 0; j <= Gy; j++) {
      for(int k = 0; k < N; k++) {
        chmin(dp[i + x[k]][j + y[k]], dp[i][j] + z[k]);
      }
      chmin(dp[i + 1][j], dp[i][j] + F);
      chmin(dp[i][j + 1], dp[i][j] + F);
    }
  }

  cout << dp[Gx][Gy] << endl;

}