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

#define int long long

#define rep(i,s,n) for(int i = s;i<n;i++)
#define repe(i,s,n) for(int i = s;i<=n;i++)
#define rrep(i,s,n) for(int i = (n)-1;i>=(s);i--)
#define all(v) (v).begin(),(v).end()
#define pb push_back
#define fi first
#define se second
#define chmin(a,b) a=b
#define chmax(a,b) a=b
typedef long long ll;
typedef pair<int,int>pint;
typedef vector<int>vint;
typedef vector<pint>vpint;
typedef pair<pint,int> P1;
typedef pair<int,pint> P2;
typedef pair<pint,pint>PP;
static const ll maxLL = (ll)1 << 62;
const ll MOD=1000000007;
const ll INF=1e18;
int dx[]={0,0,1,-1};
int dy[]={-1,1,0,0};

int GX,GY,N,F;
int x[55],y[55],c[55];
int dp[55][222][222];

signed main(){
    cin.tie(0);
	ios::sync_with_stdio(false);
    cin>>GX>>GY>>N>>F;
    rep(i,0,N)cin>>x[i]>>y[i]>>c[i];
    
    rep(j,0,GY+1){
        rep(k,0,GX+1){
            dp[0][j][k]=(j+k)*F;
        }
    }
    
    rep(i,0,N){
        rep(j,0,GY+1){
            rep(k,0,GX+1){
                if(j>=y[i]&&k>=x[i]){
                    dp[i+1][j][k]=min(dp[i][j][k],dp[i][j-y[i]][k-x[i]]+c[i]);
                }else{
                    dp[i+1][j][k]=dp[i][j][k];
                }
            }
        }
    }
    cout<<dp[N][GY][GX]<<"\n";
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    return 0;
}