#include <bits/stdc++.h>
using namespace std;
long long n,m,k,arr[1000000],ans,sum;
int main(){
	cin>>n>>m>>k;
	for(int i=1;i<=n;i++){
		cin>>arr[i];
	}
	sort(arr+1,arr+1+n,greater<int>());
	bool flag=false;
	for(int i=1;;i+=m){
		if(flag){
			break;
		}
		if(i>=(n-m)){
			flag=true;
		}
		sum=0;
		if(!flag){
			for(int j=i;j<=i+m;j++){
				sum+=arr[j];
			}
		}else{
			for(int j=i;j<=n;j++){
				sum+=arr[j];
			}
		}
		if(sum>k){
			ans+=k;
		}else{
			ans+=sum;
		}
	}
	cout<<ans;
}

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NSAyIDgKMiA3IDEgOCA0

5 2 8
2 7 1 8 4