#include <iostream>
#include <vector>
#include <algorithm>
#include <string>
#include <numeric>
#include <utility>
#include <tuple>

#define REP(i, a, b) for (int i = int(a); i < int(b); i++)
using namespace std;
using ll = long long int;
using P = pair<int, int>;

// clang-format off
#ifdef _DEBUG_
#define dump(...) do{ cerr << __LINE__ << ":\t" << #__VA_ARGS__ << " = "; PPPPP(__VA_ARGS__); cerr << endl; } while(false)
template<typename T> void PPPPP(T t) { cerr << t; }
template<typename T, typename... S> void PPPPP(T t, S... s) { cerr << t << ", "; PPPPP(s...); }
#else
#define dump(...) do{ } while(false)
#endif
template<typename T> vector<T> make_v(size_t a, T b) { return vector<T>(a, b); }
template<typename... Ts> auto make_v(size_t a, Ts... ts) { return vector<decltype(make_v(ts...))>(a, make_v(ts...)); }
template<typename T> bool chmin(T &a, T b) { if (a > b) {a = b; return true; } return false; }
template<typename T> bool chmax(T &a, T b) { if (a < b) {a = b; return true; } return false; }
template<typename T> void print(T a) { cout << a << endl; }
template<typename T, typename... Ts> void print(T a, Ts... ts) { cout << a << ' '; print(ts...); }
template<typename T> istream &operator,(istream &in, T &t) { return in >> t; }
// clang-format on

int main() {
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    int gx, gy, n, f;
    cin, gx, gy, n, f;
    vector<ll> x(n), y(n), c(n);
    REP(i, 0, n) {
        cin, x[i], y[i], c[i];
    }
    const ll inf = 1LL << 60;
    auto dp = make_v(gy + 1, gx + 1, inf);
    dp[0][0] = 0;
    REP(k, 0, n) {
        for (int i = gy; i >= 0; i--) {
            for (int j = gx; j >= 0; j--) {
                if (dp[i][j] != inf && i + y[k] <= gy && j + x[k] <= gx) {
                    chmin(dp[i + y[k]][j + x[k]], dp[i][j] + c[k]);
                }
            }
        }
    }
    ll ans = inf;
    REP(i, 0, gy + 1) {
        REP(j, 0, gx + 1) {
            chmin(ans, dp[i][j] + (gy - i + gx - j) * f);
        }
    }
    cout << ans << endl;
    return 0;
}