#define _CRT_SECURE_NO_WARNINGS
#include "bits/stdc++.h"
#include <random>
//#include "util.k"

using namespace std;

//呪文
#define DUMPOUT cout
#define dump(...) DUMPOUT<<"  ";DUMPOUT<<#__VA_ARGS__<<" :["<<__LINE__<<":"<<__FUNCTION__<<"]"<<endl;DUMPOUT<<"    ";dump_func(__VA_ARGS__)

typedef unsigned uint; typedef long long ll; typedef unsigned long long ull; typedef pair<int, int> pii; typedef pair<ll, ll> pll; typedef pair<double, double> pdd; typedef pair<string, string> pss;
template <typename _KTy, typename _Ty> ostream& operator << (ostream& ostr, const pair<_KTy, _Ty>& m) { ostr << "{" << m.first << ", " << m.second << "}"; return ostr; }
template <typename _KTy, typename _Ty> ostream& operator << (ostream& ostr, const map<_KTy, _Ty>& m) { if (m.empty()) { ostr << "{ }"; return ostr; } ostr << "{" << *m.begin(); for (auto itr = ++m.begin(); itr != m.end(); itr++) { ostr << ", " << *itr; } ostr << "}"; return ostr; }
template <typename _Ty> ostream& operator << (ostream& ostr, const vector<_Ty>& v) { if (v.empty()) { ostr << "{ }"; return ostr; } ostr << "{" << v.front(); for (auto itr = ++v.begin(); itr != v.end(); itr++) { ostr << ", " << *itr; }	ostr << "}"; return ostr; }
template <typename _Ty> ostream& operator << (ostream& ostr, const set<_Ty>& s) { if (s.empty()) { ostr << "{ }"; return ostr; } ostr << "{" << *(s.begin()); for (auto itr = ++s.begin(); itr != s.end(); itr++) { ostr << ", " << *itr; }	ostr << "}"; return ostr; }
template <typename _Ty> ostream& operator << (ostream& ostr, const stack<_Ty>& s) { if (s.empty()) { ostr << "{ }"; return ostr; } stack<_Ty> t(s); ostr << "{" << t.top(); t.pop(); while (!t.empty()) { ostr << ", " << t.top(); t.pop(); } ostr << "}";	return ostr; }
template <typename _Ty> ostream& operator << (ostream& ostr, const list<_Ty>& l) { if (l.empty()) { ostr << "{ }"; return ostr; } ostr << "{" << l.front(); for (auto itr = ++l.begin(); itr != l.end(); ++itr) { ostr << ", " << *itr; } ostr << "}"; return ostr; }
template <typename _KTy, typename _Ty> istream& operator >> (istream& istr, pair<_KTy, _Ty>& m) { istr >> m.first >> m.second; return istr; }
template <typename _Ty> istream& operator >> (istream& istr, vector<_Ty>& v) { for (size_t i = 0; i < v.size(); i++) istr >> v[i]; return istr; }
namespace aux { // print tuple
	template<typename Ty, unsigned N, unsigned L> struct tp { static void print(ostream& os, const Ty& v) { os << get<N>(v) << ", "; tp<Ty, N + 1, L>::print(os, v); } };
	template<typename Ty, unsigned N> struct tp<Ty, N, N> { static void print(ostream& os, const Ty& value) { os << get<N>(value); } };
}
template<typename... Tys> ostream& operator<<(ostream& os, const tuple<Tys...>& t) { os << "{"; aux::tp<tuple<Tys...>, 0, sizeof...(Tys)-1>::print(os, t); os << "}"; return os; }

template<typename A, size_t N, typename T> inline void Fill(A(&array)[N], const T &val) { std::fill((T*)array, (T*)(array + N), val); }

void dump_func() { DUMPOUT << endl; }
template <class Head, class... Tail> void dump_func(Head&& head, Tail&&... tail) { DUMPOUT << head; if (sizeof...(Tail) == 0) { DUMPOUT << " "; } else { DUMPOUT << ", "; } dump_func(std::move(tail)...); }

#define PI 3.14159265358979323846
#define EPS 1e-11
#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define REP(i,n)  FOR(i,0,n)
#define all(x) (x).begin(), (x).end()
#define SZ(x) ((int)(x).size())
#define fake false



int dp[64][128][128];

void print_state(int t, int Gy, int Gx) {
	for (int i = 0; i <= Gy; i++) {
		for (int j = 0; j <= Gx; j++) {
			printf("%2d ", dp[t][i][j]);
		}
		cout << endl;
	}
	cout << endl;
}

int main()
{
	//clock_t start, end;
	//start = clock();

	//cin.tie(0);
	//ios::sync_with_stdio(false);

	Fill(dp, -1);

	int Gx, Gy, N, F;
	cin >> Gx >> Gy >> N >> F;

	vector<int> vx(N), vy(N), vc(N);
	REP(i, N) cin >> vx[i] >> vy[i] >> vc[i];

	for (int i = 0; i <= Gy; i++) {
		for (int j = 0; j <= Gx; j++) {
			dp[0][i][j] = F * (i + j);
		}
	}
	
	//print_state(0, Gy, Gx);

	REP(t, N) {
		int y = vy[t], x = vx[t], c = vc[t];
		REP(i, Gy + 1) REP(j, Gx + 1) {
			//print_state(t + 1, Gy, Gx);
			if (i + y <= Gy && j + x <= Gx) {
				int ny = i + y, nx = j + x;
				if (dp[t][i][j] + c < dp[t][ny][nx]) {
					dp[t + 1][ny][nx] = dp[t][i][j] + c;
					//print_state(t + 1, Gy, Gx);
					for (int ii = 0; ii + ny <= Gy; ii++) {
						for (int jj = 0; jj + nx <= Gx; jj++) {
							int my = ii + ny, mx = jj + nx;
							if (dp[t + 1][ny][nx] + F * (ii + jj) < dp[t][my][mx]) {
								dp[t + 1][my][mx] = dp[t + 1][ny][nx] + F * (ii + jj);
								//print_state(t + 1, Gy, Gx);
							}
						}
					}
				}
			}
			dp[t + 1][i][j] = (dp[t + 1][i][j] < 0 ? dp[t][i][j] : min(dp[t + 1][i][j], dp[t][i][j]));
		}
	}
	
	cout << dp[N][Gy][Gx] << endl;



	//end = clock();
	//printf("%d msec.\k", end - start);

	return 0;
}