#include <iostream>
#include <algorithm>
using namespace std;

struct crystal{int x,y,c, otoku;};

bool cospa( const crystal &cry1, const crystal &cry2 ){
    if(cry1.otoku != cry2.otoku) return cry1.otoku < cry2.otoku;
    else return cry1.x+cry1.y < cry2.x+cry2.y;
}

int main(){
    int Gx, Gy, N, F;
    cin >> Gx >> Gy >> N >> F;

    crystal crystals[N];
    for(int i=0; i<N; i++){
        cin >> crystals[i].x >> crystals[i].y >> crystals[i].c;
        if(crystals[i].x>0 && crystals[i].y>0){
            crystals[i].otoku = crystals[i].c - F*(crystals[i].x + crystals[i].y);
        }else{
            crystals[i].otoku = 0;
        }
    }
    sort(crystals, crystals+N, cospa);

    //moveCost[i][j]=(i,j)に行くのにかかる最小料金
    int moveCost[Gx+1][Gy+1];
    for(int i=0; i<=Gx; i++){
        for(int j=0; j<=Gy; j++){
            moveCost[i][j] = (i+j)*F; //全部歩いたときのコスト
        }
    }

    for(int k=0; crystals[k].otoku<0; k++){
        for(int i=Gx; i>=crystals[k].x; i--){
            for(int j=Gy; j>=crystals[k].y; j--){
                moveCost[i][j] = moveCost[i-crystals[k].x][j-crystals[k].y] + crystals[k].c;
            }
        }
    }

    cout << moveCost[Gx][Gy] << endl;

    return 0;
}