#include <bits/stdc++.h>
using namespace std;

typedef long long ll;
typedef unsigned long long ull;
typedef pair<int, int> P;
typedef pair<ll, pair<ll, ll> > P3;

const ll MOD = ll(1e9 + 7);
const ll LLINF = LLONG_MAX;
const int IINF = INT_MAX;
const int MAX_N = int(1e5) + 5;
const double EPS = 1e-8;
int dx[] = {1, 0, -1, 0}, dy[] = {0, 1, 0, -1};
#define SORT(v) sort((v).begin(), (v).end())
#define SORTR(v) sort((v).rbegin(), (v).rend())
#define REP(i, n) for (int i = 0; i < n; i++)
#define REPR(i, n) for (int i = n; i >= 0; i--)
#define FOR(i, m, n) for (ll i = m; i < n; i++)
#define ALL(v) ((v).begin(), (v).end())

int gx, gy, n, f, x[55], y[55], c[55], dp[55][105][105];

int main() {
    
    cin >> gx >> gy >> n >> f;
    REP(i,n)cin >> x[i] >> y[i] >> c[i];
    REP(i, gx + 1) REP(j, gy + 1) REP(k, n + 1) dp[k][i][j] = (i+j)*f;
    dp[0][0][0] = 0;

    REP(i, gx+1) {
        REP(j, gy+1) {
            REP(k, n) {
                if(x[k]<=i && y[k]<=j)dp[k+1][i][j] = min(dp[k+1][i][j],dp[k][i-x[k]][j-y[k]]+c[k]);
                if(i>0){
                    dp[k+1][i][j] = min(dp[k+1][i][j],dp[k][i-1][j]+f);
                    dp[k+1][i][j] = min(dp[k+1][i][j],dp[k+1][i-1][j]+f);
                }
                if(j>0){
                    dp[k+1][i][j] = min(dp[k+1][i][j],dp[k][i][j-1]+f);
                    dp[k+1][i][j] = min(dp[k+1][i][j],dp[k+1][i][j-1]+f);
                }
                dp[k+1][i][j] = min(dp[k+1][i][j],dp[k][i][j]);
            }
        }
    }
    cout << dp[n][gx][gy] << endl;
    return 0;
}