#include <iostream>
#include<vector>
#include<algorithm>
#include<string>
#include<map>
#include<set>
#include<stack>
#include<queue>
#include<math.h>
using namespace std;
typedef long long ll;
#define int long long
#define double long double
typedef vector<int> VI;
typedef pair<int, int> pii;
typedef vector<pii> VP;
typedef vector<string> VS;
typedef priority_queue<int> PQ;
template<class T>bool chmax(T &a, const T &b) { if (a < b) { a = b; return 1; } return 0; }
template<class T>bool chmin(T &a, const T &b) { if (b < a) { a = b; return 1; } return 0; }
#define fore(i,a) for(auto &i:a)
#define REP(i,n) for(int i=0;i<n;i++)
#define eREP(i,n) for(int i=0;i<=n;i++)
#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define eFOR(i,a,b) for(int i=(a);i<=(b);++i)
#define SORT(c) sort((c).begin(),(c).end())
#define rSORT(c) sort((c).rbegin(),(c).rend())
#define LB(x,a) lower_bound((x).begin(),(x).end(),(a))
#define UB(x,a) upper_bound((x).begin(),(x).end(),(a))
#define INF 1000000000
#define LLINF 9223372036854775807
#define mod 1000000007
#define eps 1e-12 
//priority_queue<int,vector<int>, greater<int> > q2;

int N, gx, gy;
int dp[110][110];

bool is_in(int x, int y) {
	return (x <= gx && y <= gy && 0 <= y && 0 <= x);//枠の外
}

signed main() {
	cin.tie(0);
	ios::sync_with_stdio(false);

	int F; cin >> gx >> gy >> N >> F;
	vector<pair<pii, int> > A(N);
	REP(i, N)cin >> A[i].first.first >> A[i].first.second >> A[i].second;
	eREP(i, gx)eREP(j, gy)dp[i][j] = INF;
	dp[0][0] = 0;
	eREP(i, gx)eREP(j, gy) {
		if (is_in(i + 1, j))chmin(dp[i + 1][j], dp[i][j] + F);
		if (is_in(i, j + 1))chmin(dp[i][j + 1], dp[i][j] + F);
	}
	
	REP(k, N) {
		for (int i = gx; i >= 0; i--) {
			for (int j = gy; j >= 0; j--) {

				int x = i - A[k].first.first;
				int y = j - A[k].first.second;
				int c = A[k].second;
				if (is_in(x, y)) chmin(dp[i][j], dp[x][y] + c);
			}
		}
	}
	cout << dp[gx][gy] << endl;

	return 0;
}