#include <algorithm>
#include <cfloat>
#include <climits>
#include <cmath>
#include <complex>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <functional>
#include <iostream>
#include <map>
#include <memory>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <utility>
#include <vector>
 
using namespace std;
 
typedef long long ll;
 
#define sz size()
#define pb push_back
#define mp make_pair
#define fi first
#define se second
#define all(c) (c).begin(), (c).end()
#define rep(i,a,b) for(ll i=(a);i<(b);++i)
#define per(i,a,b) for(ll i=(b-1);i>=(a);--i)
#define clr(a, b) memset((a), (b) ,sizeof(a))
#define ctos(c) string(1,c)
#define print(x) cout<<#x<<" = "<<x<<endl;
 
#define MOD 1000000007

ll dp[55][110][110];

int main(){
  ll gx,gy,n,f;
  cin>>gx>>gy>>n>>f;
  vector<ll> vx;
  vector<ll> vy;
  vector<ll> vc;
  rep(i,0,n){
    ll a,b,c;
    cin>>a>>b>>c;
    vx.pb(a);
    vy.pb(b);
    vc.pb(c);
  }
  rep(i,0,55)rep(j,0,110)rep(k,0,110)dp[i][j][k] = 1000000000000LL;
  dp[0][0][0] = 0;
  rep(i,1,vx.sz+1){
    rep(j,0,105){
      rep(k,0,105){
        if(dp[i-1][j][k]!=-1){
          dp[i][min(103LL,j+vx[i-1])][min(103LL,k+vy[i-1])] = min(dp[i][min(103LL,j+vx[i-1])][min(103LL,k+vy[i-1])],dp[i-1][j][k]+vc[i-1]);     
          dp[i][j][k] = min(dp[i][j][k],dp[i-1][j][k]);
        }
      }
    }
  }
  ll mn = 1000000000000LL;
  rep(x,0,gx+1){
    rep(y,0,gy+1){
      if(dp[n][x][y]!=-1){
        mn = min(mn,dp[n][x][y]+(abs(gx-x)+abs(gy-y))*f);
      }
    }
  }
  cout << mn << endl;
  return 0;
}