#include<bits/stdc++.h>
#define rep(i,a,b) for(int i=int(a);i<int(b);++i)
using namespace std;
typedef long long ll;
int INF = (1LL << 30) - 1;
int MOD = 1e9+7;
main(){
    int GX,GY,N,F;
    cin >> GX >> GY >> N >> F;
    vector<int> X(N),Y(N),C(N);
    rep(i,0,N){
        cin >> X[i] >> Y[i] >> C[i];
    }
    int dp[51][101][101];
    rep(i,0,N+1)rep(j,0,GX+1)rep(k,0,GY+1){
        dp[i][j][k] = INF;
    }
    dp[0][0][0] = 0;
    rep(i,0,N){
        rep(j,0,GX+1)rep(k,0,GY+1){
            dp[i+1][j][k] = dp[i][j][k];
            if(j < X[i] || k < Y[i])continue;
            dp[i+1][j][k] = min(dp[i+1][j][k], dp[i][j - X[i]][k - Y[i]] + C[i]);
        }
    }
    int mini = INF;
    rep(i,0,GX+1)rep(j,0,GY+1){
        mini = min(mini, dp[N][i][j] + F * (GX - i + GY - j));
    }
    cout << mini << endl;
}