#include<bits/stdc++.h>
using namespace std;
using Int = long long;
template<typename T1,typename T2> inline void chmin(T1 &a,T2 b){if(a>b) a=b;}
template<typename T1,typename T2> inline void chmax(T1 &a,T2 b){if(a<b) a=b;}


template<typename T>
vector<T> make_v(size_t a){return vector<T>(a);}

template<typename T,typename... Ts>
auto make_v(size_t a,Ts... ts){
  return vector<decltype(make_v<T>(ts...))>(a,make_v<T>(ts...));
}

template<typename T,typename V>
typename enable_if<is_class<T>::value==0>::type
fill_v(T &t,const V &v){t=v;}

template<typename T,typename V>
typename enable_if<is_class<T>::value!=0>::type
fill_v(T &t,const V &v){
  for(auto &e:t) fill_v(e,v);
}

//INSERT ABOVE HERE
signed main(){
  Int gx,gy,n,f;
  cin>>gx>>gy>>n>>f;
  vector<Int> x(n),y(n),c(n);
  for(Int i=0;i<n;i++) cin>>x[i]>>y[i]>>c[i];

  const Int INF = 1e15;
  auto dp=make_v<Int>(200,200);
  fill_v(dp,INF);
  dp[0][0]=0;
  for(Int i=0;i<n;i++)
    for(Int a=199;a>=0;a--)
      for(Int b=199;b>=0;b--)
        if(a+y[i]<200&&b+x[i]<200)
          chmin(dp[a+y[i]][b+x[i]],dp[a][b]+c[i]);

  Int ans=INF;
  for(Int i=0;i<=gy;i++)
    for(Int j=0;j<=gx;j++)
      chmin(ans,dp[i][j]+(gy-i+gx-j)*f);
  
  cout<<ans<<endl;
  return 0;
}