#include <bits/stdc++.h>
#define ll long long
#define INF 1000000005
#define MOD 1000000007
#define EPS 1e-10
#define rep(i,n) for(int i=0;i<(int)n;++i)
#define each(a, b) for(auto (a): (b))
#define all(v) (v).begin(),(v).end()
#define fi first
#define se second
#define pb push_back
#define show(x) cout <<#x<<" = "<<(x)<<endl
#define spair(p) cout <<#p<<": "<<p.fi<<" "<<p.se<<endl
#define svec(v) cout<<#v<<":";rep(kbrni,v.size())cout<<" "<<v[kbrni];cout<<endl
#define sset(s) cout<<#s<<":";each(kbrni,s)cout <<" "<<kbrni;cout<<endl

using namespace std;

typedef pair<int,int>P;

const int MAX_N = 102;

int dp[MAX_N][MAX_N];

int main()
{
    int l,h,n,f;
    cin >> l >> h >> n >> f;
    vector<int> x(n),y(n),c(n);
    rep(i,n){
        cin >> x[i] >> y[i] >> c[i];
    }
    rep(i,l+1){
        rep(j,h+1){
            dp[i][j] = (i+j)*f;
        }
    }
    rep(i,n){
        for(int j=l+1;j>=0;j--){
            for(int k=h+1;k>=0;k--){
                if(j - x[i] >= 0 && k - y[i] >= 0){
                    dp[j][k] = min(dp[j][k],dp[j-x[i]][k-y[i]] + c[i]);
                }
            }
        }
    }
    cout << dp[l][h] << endl;
    return 0;
}