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

#define fi first
#define se second
#define repl(i,a,b) for(int i=(int)(a);i<(int)(b);i++)
#define rep(i,n) repl(i,0,n)
#define each(itr,v) for(auto itr:v)
#define pb(s) push_back(s)
#define mp(a,b) make_pair(a,b)
#define all(x) (x).begin(),(x).end()
#define dbg(x) cout<<#x"="<<x<<endl
#define maxch(x,y) x=max(x,y)
#define minch(x,y) x=min(x,y)
#define uni(x) x.erase(unique(all(x)),x.end())
#define exist(x,y) (find(all(x),y)!=x.end())
#define bcnt(x) bitset<32>(x).count()

typedef long long ll;
typedef unsigned long long ull;
typedef pair<int, int> P;
typedef pair<P, int> PPI;
typedef pair<ll, ll> PL;
typedef pair<P, ll> PPL;

#define INF 1e17

#define MAX_N 1000

ll gx,gy,n,f;
ll dx[55],dy[55],c[55];
ll dp[333][333];

int main(){
	cin.sync_with_stdio(false);
  cin>>gx>>gy>>n>>f;
  rep(i,n)cin>>dx[i]>>dy[i]>>c[i];
  rep(i,333)rep(j,333)dp[i][j]=(i+j)*f;
  rep(k,n){
    for(int len=222;len>=0;len--)for(int i=111;i>=0;i--){
      int j=len-i;
      if(j<0)continue;
      minch(dp[i+dy[k]][j+dx[k]],dp[i][j]+c[k]);
    }
  }
  cout<<dp[gy][gx]<<endl;
	return 0;
}