#include <bits/stdc++.h>
using namespace std;
#define int long long
using ll=long long;
using vi=vector<int>;
using vl=vector<long long>;
using pii=pair<int,int>;
using pll=pair<long long,long long>;
#define ITR(i,c) for(auto i=begin(c);i!=end(c);++i)
#define FORE(x,c) for(auto &x:c)
#define FOR(i,a,n) for(int i=a,i##_len=(int)(n);i<i##_len;++i)
#define REP(i,n) FOR(i,0,n)
#define RREP(i,n) for(int i=(int)(n);i>=0;--i)
#define ALL(c) begin(c),end(c)
#define RALL(c) rbegin(c),rend(c)   // c++14
#define SZ(c) ((int)c.size())
#define EXIST(c,x) (c.find(x)!=end(c))
#define OUTOFRANGE(y,x,h,w) (y<0||x<0||y>=h||x>=w)
#define dump(...)
const int DX[9]={0,1,0,-1,1,1,-1,-1,0},DY[9]={-1,0,1,0,-1,1,1,-1,0};
#define INF (1001001001)
#define INFLL (1001001001001001001ll)
template<class T> ostream& operator << (ostream &os,const vector<T> &v) {
    ITR(i,v) os << *i << (i==end(v)-1 ? "" : "\n"); return os; }
template<class T> istream& operator >> (istream &is,vector<T> &v) {
    ITR(i,v) is >> * i; return is; }
template<class T> istream& operator >> (istream &is, pair<T,T> &p) {
        is >> p.first >> p.second; return is; }
template<class T>bool chmax(T &a,const T &b){if(a<b){a=b;return 1;}return 0;}
template<class T>bool chmin(T &a,const T &b){if(b<a){a=b;return 1;}return 0;}
//------------------------------------------------------------------------------
struct before_main_function {
    before_main_function() {
        #ifdef int
            #undef INF
            #define INF INFLL
            #define stoi stoll
        #endif
        cin.tie(0);ios::sync_with_stdio(false);
        cout<<setprecision(15)<<fixed;
    }
} before_main_function;
//------------------------------------------------------------------------------

signed main() {
    int gx,gy;
    cin>>gx>>gy;
    int N,F;
    cin>>N>>F;
    vi x(N),y(N),c(N);
    REP(i,N) {
        cin>>x[i]>>y[i]>>c[i];
    }
    vector<vector<vector<int>>> dp(51,vector<vector<int>>(101,vector<int>(101,INF)));
    chmin(dp[0][x[0]][y[0]],c[0]);
    chmin(dp[0][1][0],F);
    chmin(dp[0][0][1],F);
    chmin(dp[0][0][0],0ll);
    FOR(i,0,N-1) {
        REP(j,101) {
            REP(k,101) {
                if(dp[i][j][k]!=INF) {
                    if(j+x[i+1]<=gx && k+y[i+1]<=gy)
                        chmin(dp[i+1][j+x[i+1]][k+y[i+1]],dp[i][j][k]+c[i+1]);
                    chmin(dp[i+1][j][k],dp[i][j][k]);
                }
            }
        }
    }
    REP(j,101) {
        REP(k,101) {
            if(dp[N-1][j][k]!=INF) {
                chmin(dp[N-1][gx][gy],dp[N-1][j][k]+(gx-j+gy-k)*F);
            }
        }
    }
    cout<<dp[N-1][gx][gy]<<endl;
    return 0;
}