#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef long double ld;
#define rep(i,n) for (int i = 0; i < (n); ++i)
template<class T>bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T>bool chmin(T &a, const T &b) { if (b<a) { a=b; return 1; } return 0; }
const ll INF=1LL<<60;
const int inf=(1<<30)-1;
const int mod=1e9+7;
int dx[8]={1,0,-1,0,-1,-1,1,1};
int dy[8]={0,1,0,-1,-1,1,-1,1};
int main(){
    cin.tie(0);
    ios::sync_with_stdio(false);
    int gx,gy,n,f;cin >> gx >> gy >> n >> f;
    vector<int> x(n),y(n),c(n);
    rep(i,n){
        cin >> x[i] >> y[i] >> c[i];
    }
    vector<vector<vector<int>>> dp(n+1,vector<vector<int>>(gx+1,vector<int>(gy+1,inf)));
    dp[0][0][0]=0;
    rep(i,n){
        rep(j,gx+1){
            rep(k,gy+1){
                chmin(dp[i+1][j][k],dp[i][j][k]);
                if(j+x[i]<=gx&&k+y[i]<=gy){
                    chmin(dp[i+1][j+x[i]][k+y[i]],dp[i][j][k]+c[i]);
                }
            }
        }
    }
    int ans=inf;
    rep(i,gx+1){
        rep(j,gy+1){
            chmin(ans,dp[n][i][j]+f*(gx-i+gy-j));
        }
    }
    cout << ans << endl;
}