#include <bits/stdc++.h>
#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define rep(i,n) FOR(i,0,n)
#define repr(i,n) for(int i=(n)-1;0<=i;--i)
#define each(e,v) for(auto&& e:(v))
#define all(v) begin(v),end(v)
#define DUMP(x) cerr<<#x<<": "<<(x)<<endl
#define DEBUG(x) cerr<<#x<<": "<<(x)<<" (L"<<__LINE__<<")"<<endl
using namespace std;
using vint = vector<int>;
using vdouble = vector<double>;
using vstring = vector<string>;
using ll = long long;
template <class T> void chmin(T& a, const T& b) { a = min(a, b); }
template <class T> void chmax(T& a, const T& b) { a = max(a, b); }

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

struct Crystal {
    int x, y, c;
    Crystal() = default;
    Crystal(int x, int y, int c): x(x), y(y), c(c) {}
};

bool operator > (const Crystal& a, const Crystal& b) {
    return ((a.x + a.y) / a.c) > ((b.x + b.y) / b.c);
}

int main() {
    int gx, gy, n, f; cin >> gx >> gy >> n >> f;
    vector<Crystal> crs;
    rep(i, n) {
        int x, y, c; cin >> x >> y >> c;
        if((x + y) * f <= c) continue;
        crs.push_back(Crystal(x, y, c));
    }
    int x = 0, y = 0, cost = 0;
    sort(all(crs), greater<Crystal>());
    const int cn = crs.size();
    rep(i, cn) {
        if(x + crs[i].x <= gx && y + crs[i].y <= gy) {
            x += crs[i].x;
            y += crs[i].y;
            cost += crs[i].c;
        }
    }
    cost += (gx - x + gy - y) * f;
    cout << cost << endl;
    return 0;
}