#include <cstdio>
#include <cstdlib>
#include <cmath>
#include <cstring>

#include <iostream>
#include <string>
#include <algorithm>
#include <vector>
#include <queue>
#include <stack>
#include <map>
#include <set>
#include <unordered_map>
#include <unordered_set>

#include <functional>
#include <cassert>

typedef long long ll;
using namespace std;

#define debug(x) cerr << #x << " = " << (x) << endl;


#define mod 1000000007 //1e9+7(prime number)
#define INF 1000000000 //1e9
#define LLINF 2000000000000000000LL //2e18
#define SIZE 100010

int dp[51][110][110];

int main(){
  int gx, gy, n, f;
  int x[51], y[51], c[51];
  
  scanf("%d%d%d%d",&gx,&gy,&n,&f);

  for(int i=0;i<n;i++){
    scanf("%d%d%d",x+i, y+i, c+i);
  }

  
  for(int i=0;i<=gx;i++){
    for(int j=0;j<=gy;j++){
      for(int k=0;k<51;k++){
        dp[k][i][j] = INF;
      }
    }
  }

  dp[0][0][0] = 0;
  
  for(int i=0;i<=gx;i++){
    for(int j=0;j<=gy;j++){

      for(int k=0;k<=n;k++){
        
        for(int r=k;r<n;r++){
          if(i+x[r] <= gx && j+y[r] <= gy)
            dp[r+1][i+x[r]][j+y[r]] = min(dp[r+1][i+x[r]][j+y[r]],
                                          dp[k][i][j] + c[r]);
        }

        if(i+1 <= gx)
          dp[k][i+1][j] = min(dp[k][i+1][j],dp[k][i][j] + f);
        
        if(j+1 <= gy)
          dp[k][i][j+1] = min(dp[k][i][j+1],dp[k][i][j] + f);
      }
      
    }
  }

  int ans = INF;
  
  for(int i=0;i<=n;i++){
    ans = min(ans,dp[i][gx][gy]);
  }

  printf("%d\n",ans);
  
  return 0;
}