#include "bits/stdc++.h"
using namespace std;
#define int long long
#define FOR(i, a, b) for(int i=(a);i<(b);i++)
#define RFOR(i, a, b) for(int i=(b-1);i>=(a);i--)
#define REP(i, n) for(int i=0; i<(n); i++)
#define RREP(i, n) for(int i=(n-1); i>=0; i--)
#define ALL(a) (a).begin(),(a).end()
#define UNIQUE_SORT(l) sort(ALL(l)); l.erase(unique(ALL(l)), l.end());
#define CONTAIN(a, b) find(ALL(a), (b)) != (a).end()
#define array2(type, x, y) array<array<type, y>, x>
#define vector2(type) vector<vector<type> >
#define out(...) printf(__VA_ARGS__)

int dxy[] = {0, 1, 0, -1, 0};

void solve();
signed main()
{
#if DEBUG
    std::ifstream in("input.txt");
    std::cin.rdbuf(in.rdbuf());
#endif
    cin.tie(0);
    ios::sync_with_stdio(false);
    solve();
    return 0;
}

/*================================*/
#if DEBUG
#define SIZE 6
#else
#define SIZE 123
#endif

int X,Y,N,F;
int DP[SIZE][SIZE];

void solve() {
    cin>>X>>Y>>N>>F;
    
    REP(x,X+1)REP(y,Y+1) {
        DP[x][y] = (x + y) * F;
    }
    int dx,dy,c;
    REP(_i,N) {
        cin>>dx>>dy>>c;
        RFOR(x,dx,X+1)RFOR(y,dy,Y+1) {
            DP[x][y] = min(DP[x][y], DP[x-dx][y-dy]+c);
        }
    }
    
    cout << DP[X][Y] << endl;
}