#include <bits/stdc++.h>
using namespace std;
#define F first
#define S second
#define pi M_PI
#define R cin>>
#define Z class
#define ll long long
#define ln cout<<'\n'
#define in(a) insert(a)
#define pb(a) push_back(a)
#define pd(a) printf("%.10f\n",a)
#define mem(a) memset(a,0,sizeof(a))
#define all(c) (c).begin(),(c).end()
#define iter(c) __typeof((c).begin())
#define rrep(i,n) for(int i=(int)(n)-1;i>=0;i--)
#define REP(i,m,n) for(int i=(int)(m);i<(int)(n);i++)
#define rep(i,n) REP(i,0,n)
#define tr(it,c) for(iter(c) it=(c).begin();it!=(c).end();it++)
template<Z A>void pr(A a){cout<<a;ln;}
template<Z A,Z B>void pr(A a,B b){cout<<a<<' ';pr(b);}
template<Z A,Z B,Z C>void pr(A a,B b,C c){cout<<a<<' ';pr(b,c);}
template<Z A,Z B,Z C,Z D>void pr(A a,B b,C c,D d){cout<<a<<' ';pr(b,c,d);}
template<Z A>void PR(A a,ll n){rep(i,n){if(i)cout<<' ';cout<<a[i];}ln;}
ll check(ll n,ll m,ll x,ll y){return x>=0&&x<n&&y>=0&&y<m;}
const ll MAX=1000000007,MAXL=1LL<<61,dx[4]={-1,0,1,0},dy[4]={0,1,0,-1};
typedef pair<int,int> P;
typedef pair<int,P> PP;

void Main() {
  int h,w,n,t;
  cin >> h >> w >> n >> t;
  h++,w++;
  PP a[n];
  rep(i,n) cin >> a[i].S.F >> a[i].S.S >> a[i].F;
  int d[h][w];
  rep(i,h)rep(j,w) d[i][j]=MAX;
  d[0][0]=0;
  rep(k,n)rrep(i,h)rrep(j,w) {
    int x=i+a[k].S.F,y=j+a[k].S.S,c=a[k].F;
    if(check(h,w,x,y)) d[x][y]=min(d[x][y],d[i][j]+c);
  }
  int ans=MAX;
  rep(i,h)rep(j,w) ans=min(ans,d[i][j]+(abs(h-i-1)+abs(w-j-1))*t);
  pr(ans);
}

int main(){ios::sync_with_stdio(0);cin.tie(0);Main();return 0;}