#include "bits/stdc++.h"
using namespace std;
#define FOR(i,j,k) for(int (i)=(j);(i)<(int)(k);++(i))
#define rep(i,j) FOR(i,0,j)
#define each(x,y) for(auto &(x):(y))
#define mp make_pair
#define mt make_tuple
#define all(x) (x).begin(),(x).end()
#define debug(x) cout<<#x<<": "<<(x)<<endl
#define smax(x,y) (x)=max((x),(y))
#define smin(x,y) (x)=min((x),(y))
#define MEM(x,y) memset((x),(y),sizeof (x))
#define sz(x) (int)(x).size()
#define pb push_back
typedef long long ll;
typedef pair<int, int> pii;
typedef vector<int> vi;
typedef vector<ll> vll;

const int inf = INT_MAX / 3;
int dp[210][210];

int main(){
    ios::sync_with_stdio(false);
    cin.tie(0);
    int gx, gy, n, f;
    cin >> gx >> gy >> n >> f;
    vi dx(n), dy(n), c(n);
    rep(i, n) {
        cin >> dx[i] >> dy[i] >> c[i];
    }

    rep(x, gx + 1)rep(y, gy + 1)dp[x][y] = inf;
    dp[0][0] = 0;
    rep(i,n){
        for (int x = gx; x >= 0; --x)for (int y = gy; y >= 0; --y) {
            smin(dp[x + dx[i]][y + dy[i]], dp[x][y] + c[i]);
        }
    }
    rep(x, gx + 1)rep(y, gy + 1) {
        smin(dp[x + 1][y], dp[x][y] + f);
        smin(dp[x][y + 1], dp[x][y] + f);
    }

    cout << dp[gx][gy] << endl;
}