#include<bits/stdc++.h>
using namespace std;
#define rep(i,a,b) for(int i=a;i<b;i++)




int GX, GY, N, F;
int X[60], Y[60], C[60];
//-----------------------------------------------------------------------------------
#define INF INT_MAX/2
int dst[1010][1010];
bool vis[1010][1010];
int sol() {
	rep(i, 0, 101) rep(j, 0, 101) dst[i][j] = INF;
	priority_queue<pair<int, int>> que;
	que.push({0, 0});
	dst[0][0] = 0;

	while (!que.empty()) {
		auto q = que.top(); que.pop();

		int x = q.second % 1010;
		int y = q.second / 1010;
		int c = -q.first;

		if (y == GY && x == GX) return c;

		if (vis[y][x]) continue;
		vis[y][x] = true;

		rep(i, 0, N) {
			int yy = y + Y[i];
			int xx = x + X[i];

			if (GY < yy) continue;
			if (GX < xx) continue;
			if (vis[yy][xx]) continue;

			int nc = c + C[i];
			if (nc < dst[yy][xx]) {
				dst[yy][xx] = nc;
				que.push({ -nc, yy * 1010 + xx });
			}
		}
	}

	return -1;
}
//-----------------------------------------------------------------------------------
int main() {
	cin >> GX >> GY >> N >> F;
	rep(i, 0, N) cin >> X[i] >> Y[i] >> C[i];

	X[N] = 0; Y[N] = 1; C[N] = F; N++;
	X[N] = 1; Y[N] = 0; C[N] = F; N++;

	cout << sol() << endl;
}