#include <bits/stdc++.h>

using namespace std;

#define fst(t) std::get<0>(t)
#define snd(t) std::get<1>(t)
#define thd(t) std::get<2>(t)

using ll = long long;
using P = std::tuple<int,int>;

const int dx[8] = {-1, 1, 0, 0, -1, -1, 1, 1}, dy[8] = {0, 0, -1, 1, -1, 1, -1, 1};

int Gx, Gy, N, F;
int Xs[100], Ys[100], Cs[100];
int dp[200][200][200];

int rec(int x, int y, int n){
    if(x == Gx && y == Gy){
        return 0;
    }
    if(dp[y][x][n] != -1){
        return dp[y][x][n];
    }
    // printf("%d, %d, %d\n", x, y, n);

    int res = (Gx - x + Gy - y) * F; //rec(x, y, n+1);

    for(int i=n;i<N;++i){
        int nx = x + Xs[i], ny = y + Ys[i];
        if(nx > Gx || ny > Gy){continue;}

        res = min(res, Cs[i] + rec(nx, ny, i+1));        
    }

    return dp[y][x][n] = res;
}

int main(){
    std::cin.tie(nullptr);
    std::ios::sync_with_stdio(false);

    memset(dp, -1, sizeof(dp));
    
    std::cin >> Gx >> Gy >> N >> F;

    for(int i=0;i<N;++i){
        std::cin >> Xs[i] >> Ys[i] >> Cs[i];
    }

    std::cout << rec(0, 0, 0) << std::endl;
}