#include <cstdio>
#include <iostream>
#include <string>
#include <sstream>
#include <stack>
#include <algorithm>
#include <cmath>
#include <queue>
#include <map>
#include <set>
#include <cstdlib>
#include <bitset>
#include <tuple>
#include <assert.h>
#include <deque>
#include <bitset>
#include <iomanip>
#include <limits>
#include <chrono>
#include <random>
#include <array>
#include <unordered_map>
#include <functional>
#include <complex>

template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; }

const long long MAX = 5100000;
const long long INF = 1LL << 60;
const long long mod = 1000000007LL;
//const long long mod = 998244353LL;

using namespace std;
typedef unsigned long long ull;
typedef long long ll;

ll dp[150][150][70];
ll dh[2] = { 1,0 };
ll dw[2] = { 0,1 };
int main()
{
	/*
	cin.tie(nullptr);
	ios::sync_with_stdio(false);
	*/

	ll gh, gw, n, f; scanf("%lld %lld %lld %lld", &gh, &gw, &n, &f);
	ll H = gh + 1;
	ll W = gw + 1;
	vector<ll> x(n), y(n), c(n);
	for (ll i = 0; i < n; i++) scanf("%lld %lld %lld", &x[i], &y[i], &c[i]);
	for (ll i = 0; i <= gh; i++)for (ll j = 0; j <= gw; j++)for (ll k = 0; k <= n; k++) dp[i][j][k] = INF;
	dp[0][0][0] = 0;
	for (ll k = 0; k < n; k++) {
		for (ll i = 0; i <= gh; i++) {
			for (ll j = 0; j <= gw; j++) {
				for (ll l = 0; l < 2; l++) {
					ll nh = i + dh[l];
					ll nw = j + dw[l];
					if (nh >= H || nw >= W) continue;
					chmin(dp[nh][nw][k + 1], dp[i][j][k] + f);
				}
				chmin(dp[i][j][k + 1], dp[i][j][k]);
				ll nh = i + x[k];
				ll nw = j + y[k];
				if (nh >= H || nw >= W) continue;
				chmin(dp[nh][nw][k + 1], dp[i][j][k] + c[k]);
			}
		}
	}
	cout << dp[gh][gw][n] << endl;
	return 0;
}