#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];
bool flag[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;
  }
  int min_=(X+Y)*f;
  REP(i,X+1)REP(j,Y+1)flag[i][j]=false;
  REP(k,n){
    if(c[k]>(x[k]+y[k])*f)continue;
    flag[0][0]=true;
    for(int i=X;i>=0;i--)for(int j=Y;j>=0;j--){
      int xk=i+x[k];
      int yk=j+y[k];
      if(xk>X||yk>Y||flag[i][j]==false)continue;
      if(dp[xk][yk]>dp[i][j]+c[k]){
        dp[xk][yk]=dp[i][j]+c[k];
        flag[xk][yk]=true;
        min_=min(min_,dp[xk][yk]+(X+Y-xk-yk)*f);
      }
    }
  }
  print(min_);
}