#define _USE_MATH_DEFINES
#include <cstdio>
#include <iostream>
#include <sstream>
#include <fstream>
#include <iomanip>
#include <algorithm>
#include <cmath>
#include <complex>
#include <string>
#include <vector>
#include <list>
#include <queue>
#include <stack>
#include <set>
#include <map>
#include <bitset>
#include <numeric>
#include <limits>
#include <climits>
#include <cfloat>
#include <functional>
#include <iterator>
using namespace std;

const int INF = INT_MAX / 2;

int main()
{
    int w, h, n, f;
    cin >> w >> h >> n >> f;

    vector<vector<int> > dp(h+1, vector<int>(w+1, INF));
    dp[0][0] = 0;
    for(int i=0; i<n; ++i){
        int dx, dy, c;
        cin >> dx >> dy >> c;
        for(int y=h-dy; y>=0; --y){
            for(int x=w-dx; x>=0; --x){
                int y2 = y + dy;
                int x2 = x + dx;
                dp[y2][x2] = min(dp[y2][x2], dp[y][x] + c);
            }
        }
    }

    int ans = INF;
    for(int y=0; y<=h; ++y){
        for(int x=0; x<=w; ++x){
            int dist = abs(h - y) + abs(w - x);
            ans = min(ans, dp[y][x] + f * dist);
        }
    }
    cout << ans << endl;

    return 0;
}