#include <bits/stdc++.h>
#define FOR(i,a,b) for (int i=(a);i<(b);i++)
#define FORR(i,a,b) for (int i=(a);i>=(b);i--)
#define pb push_back

using namespace std;
typedef long long ll;
typedef pair<int,int> pii;
typedef vector<int> vi;
typedef set<int> si;
const int inf = 1e9;
const int mod = 1e9+7;
int x, y, n, f;
ll dp[101][101];
main(){
  cin.tie(0);
  ios::sync_with_stdio(false);
  cin >> x >> y >> n >> f;
  FOR(i, 0, 101)FOR(j, 0, 101)dp[i][j] = inf;
  dp[0][0] = 0;
  FOR(i, 0, n){
    int w, h, c;
    cin >> w >> h >> c;
    FORR(_x, x - w, 0){
      FORR(_y, y - h, 0){
        dp[_y + h][_x + w] = min(dp[_y + h][_x + w], dp[_y][_x] + c);
      }
    }
  }
  ll ans = inf;
  FOR(i, 0, x + 1){
    FOR(j, 0, y + 1){
      ans = min(ans, (x - i + y - j) * f + dp[j][i]);
    }
  }
  cout << ans << endl;
}