#include "bits/stdc++.h"
using namespace std;
#define print(x) cout<<x<<endl;
#define rep(i,a,b) for(int i=a;i<b;i++)
#define REP(i,a) for(int i=0;i<a;i++)
#define printall(n,array) for(int i=0;i<n;i++){cout<<array[i]<<" ";}cout<<endl;
typedef long long ll;
typedef pair<int, int> PI;
typedef pair<int, PI> V;
typedef vector<int> VE;
const ll mod = 1000000007; //10^9+7

int dp[102][102];

int main(){
  int X,Y,n,f;
  cin>>X>>Y>>n>>f;
  int x[52],y[52],c[52];
  REP(i,n){
    cin>>x[i]>>y[i]>>c[i];
  }
  REP(i,X+1)REP(j,Y+1){
    dp[i][j]=(i+j)*f;
  }
  REP(k,n){
    if(c[k]>(x[k]+y[k])*f)continue;
    REP(i,X+1)REP(j,Y+1){
      dp[i+x[k]][j+y[k]]=min(dp[i+x[k]][j+y[k]],dp[i][j]+c[k]);
      //print(i+x[i]<<" "<<j+y[i]<<" "<<dp[i+x[i]][j+y[i]])
    }
  }
  print(dp[X][Y]);
}