#include <algorithm>
#include <cstdio>
#include <iostream>
#include <map>
#include <cmath>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <vector>
#include <stdlib.h>
#include <stdio.h>
#include <bitset>
using namespace std;
#define FOR(I,A,B) for(int I = (A); I < (B); ++I)

int main(){
  int gy,gx,n,f;
  cin>>gx>>gy>>n>>f;
  int x[n],y[n],c[n];
  FOR(i,0,n){
    cin >> x[i] >> y[i] >> c[i];
  }
  int dp[301][gy+1][gx+1];
  FOR(i,0,301){
    FOR(j,0,gy+1){
      FOR(k,0,gx+1){
        dp[i][j][k] = 999999;
      }
    }
  }
  dp[0][0][0] = 0;
  FOR(i,0,300){
    FOR(j,0,gy+1){
      FOR(k,0,gx+1){
        if(dp[i][j][k] == 999999) continue;
        dp[i+1][j][k] = min(dp[i+1][j][k], dp[i][j][k]);
        if(j+1 <= gy) dp[i+1][j+1][k] = min(dp[i+1][j+1][k], dp[i][j][k] + f);
        if(k+1 <= gx) dp[i+1][j][k+1] = min(dp[i+1][j][k+1], dp[i][j][k] + f);
        FOR(l,0,n){
          int nx = k + x[l], ny = j + y[l];
          if(nx > gx || ny > gy) continue;
          dp[i+1][ny][nx] = min(dp[i+1][ny][nx], dp[i][j][k] + c[l]);
        }
      }
    }
  }
  cout << dp[300][gy][gx] << endl;
  return 0;
}