#include "bits/stdc++.h"
#define REP(i,n,N) for(int i=(n); i<(N); i++)
#define RREP(i,n,N) for(int i=(N-1); i>=n; i--)
#define CK(n,a,b) ((a)<=(n)&&(n)<(b))
#define ALL(v) (v).begin(),(v).end()
#define p(s) cout<<(s)<<endl
#define p2(a,b) cout<<(a)<<" "<<(b)<<endl
#define v2(T) vector<vector<T>>
typedef long long ll;
using namespace std;
const int inf=1e9;

int gx, gy, N, F;
int dp[52][110][110];
vector<int> x(110),y(110),c(110);
int main() {
    cin>>gx>>gy>>N>>F;
    REP(i,0,N){
        cin>>x[i]>>y[i]>>c[i];
    }
    REP(i,0,N+1) REP(j,0,gy+1) REP(k,0,gx+1) dp[i][j][k]=inf;
    dp[0][0][0]=0;
    REP(i,0,N){
        REP(Y,0,gy+1){
            REP(X,0,gx+1){
                dp[i+1][Y][X]=min(dp[i+1][Y][X], dp[i][Y][X]);
                if(Y+y[i]<=gy&&X+x[i]<=gx) dp[i+1][Y+y[i]][X+x[i]] = min(dp[i+1][Y+y[i]][X+x[i]], dp[i][Y][X]+c[i]);
            }
        }
    }
    int ans=inf;
    REP(i,0,gy+1){
        REP(j,0,gx+1){
            ans=min(ans,dp[N][i][j]+F*((gy-i)+(gx-j)));
        }
    }
    p(ans);
    return 0;
}