求条

#include<bits/stdc++.h>
#define int long long
using namespace std;
int n,m,k,x;
struct node{
	int a,c,id;
}a[5005];
int dp[5005][5005];
signed main(){
	scanf("%lld%lld%lld%lld",&n,&m,&k,&x);
	m=(n-m);if(m&1) m++;
	for(int i=1;i<=n;i++){
		scanf("%lld",&a[i].a);
		a[i].id=i;
	}
	for(int i=1;i<=n;i++){
		scanf("%lld",&a[i].c);
	}
	sort(a+1,a+1+n,[](node xx,node yy){
		if(xx.c==yy.c) return xx.id<yy.id;
		return xx.c<yy.c;
	});
	for(int i=0;i<=n;i++){
		for(int j=0;j<=m;j++){
			dp[i][j]=INT_MAX;
		}
	}
	dp[0][0]=0ll;
	for(int i=1;i<=n;i++){
		for(int j=0;j<=m;j++){
			if(j&1){
				if(dp[i-1][j]!=INT_MAX) if(a[i].c==a[i-1].c) dp[i][j]=dp[i-1][j];
				if(dp[i-1][j-1]!=INT_MAX) dp[i][j]=min(dp[i][j],dp[i-1][j-1]-a[i].id*x+a[i].a);
			}else{
				if(dp[i-1][j]!=INT_MAX) dp[i][j]=dp[i-1][j];
				if(j&&dp[i-1][j-1]!=INT_MAX) if(a[i].c==a[i-1].c) dp[i][j]=min(dp[i][j],dp[i-1][j-1]+a[i].id*x+a[i].a);
			}
		}
	}
	if(dp[n][m]==INT_MAX) printf("Impossible\n");
	else printf("%lld\n",dp[n][m]);
	return 0;
}