#include <bits/stdc++.h>
using namespace std;
const int N=205;
int n,m,f[N][N],gx,gy,dx[N],dy[N],dc[N],cost;
signed main ()
{
    cin>>gx>>gy>>n>>cost;
    for (int i=1;i<=n;i++)
        cin>>dx[i]>>dy[i]>>dc[i];
    memset(f,0x7f,sizeof(f));
    f[0][0]=0;
    for (int k=1;k<=n;k++)
    	for (int i=gx;i>=0;i--)
       		for (int j=gy;j>=0;j--){
            if (i-1>=0)
                f[i][j]=min(f[i][j],f[i-1][j]+cost);
            if (j-1>=0)
                f[i][j]=min(f[i][j],f[i][j-1]+cost);
                if (i-dx[k]>=0&&j-dy[k]>=0){
                    f[i][j]=min(f[i][j],f[i-dx[k]][j-dy[k]]+dc[k]);
                }
        }
    cout<<f[gx][gy]<<endl;
    return 0;
}