#include <bits/stdc++.h>
using namespace std;
#define repl(i,a,b) for(int i=(int)(a);i<(int)(b);i++)
#define rep(i,n) repl(i,0,n)
#define mp(a,b) make_pair((a),(b))
#define pb(a) push_back((a))
#define all(x) (x).begin(),(x).end()
#define uniq(x) sort(all(x)),(x).erase(unique(all(x)),end(x))
#define fi first
#define se second
#define dbg(x) cout<<#x" = "<<((x))<<endl
template<class T,class U> ostream& operator<<(ostream& o, const pair<T,U> &p){o<<"("<<p.fi<<","<<p.se<<")";return o;}
template<class T> ostream& operator<<(ostream& o, const vector<T> &v){o<<"[";for(T t:v){o<<t<<",";}o<<"]";return o;}

#define INF 214748360
#define long long long // for codeforces

int main(){
  int h,w,n,f;
  cin>>h>>w>>n>>f;
  vector<vector<int>> vec(h+1, vector<int>(w+1, INF));
  vec[0][0] = 0;

  rep(i,n){
    int x,y,c;
    cin>>x>>y>>c;
    vector<vector<int>> nxt(vec);
    rep(j,h+1) rep(k,w+1) if(vec[j][k]<INF){
      if(j+x<=h && k+y<=w) nxt[j+x][k+y] = min(nxt[j+x][k+y], vec[j][k] + c);
    }
    swap(vec, nxt);
  }

  repl(i,1,h+1) vec[i][0] = min(vec[i][0], vec[i-1][0]+f);
  repl(i,1,w+1) vec[0][i] = min(vec[0][i], vec[0][i-1]+f);
  repl(i,1,h+1) repl(j,1,w+1) vec[i][j] = min(vec[i][j], min(vec[i-1][j], vec[i][j-1])+f);

  cout << vec[h][w] << endl;

  return 0;
}