You have m = n·k wooden staves. The i-th stave has length ai. You have to assemble n barrels consisting of k staves each, you can use any k staves to construct a barrel. Each stave must belong to exactly one barrel.
Let volume vj of barrel j be equal to the length of the minimal stave in it.

You want to assemble exactly n barrels with the maximal total sum of volumes. But you have to make them equal enough, so a difference between volumes of any pair of the resulting barrels must not exceed l, i.e. |vx - vy| ≤ l for any 1 ≤ x ≤ n and 1 ≤ y ≤ n.
Print maximal total sum of volumes of equal enough barrels or 0 if it's impossible to satisfy the condition above.
The first line contains three space-separated integers n, k and l (1 ≤ n, k ≤ 105, 1 ≤ n·k ≤ 105, 0 ≤ l ≤ 109).
The second line contains m = n·k space-separated integers a1, a2, ..., am (1 ≤ ai ≤ 109) — lengths of staves.
Print single integer — maximal total sum of the volumes of barrels or 0 if it's impossible to construct exactly n barrels satisfying the condition |vx - vy| ≤ l for any 1 ≤ x ≤ n and 1 ≤ y ≤ n.
4 2 1 2 2 1 2 3 2 2 3
7
2 1 0 10 10
20
1 2 1 5 2
2
3 2 1 1 2 3 4 5 6
0
In the first example you can form the following barrels: [1, 2], [2, 2], [2, 3], [2, 3].
In the second example you can form the following barrels: [10], [10].
In the third example you can form the following barrels: [2, 5].
In the fourth example difference between volumes of barrels in any partition is at least 2 so it is impossible to make barrels equal enough.
#include <iostream>
#include<cstring>
#include<algorithm>
#include<cstdio>
#include<queue>
using namespace std;
typedef long long ll;
const int maxn=1e5+10;
ll val[maxn];
/*
挺好的一道思维题和模拟题。。。
*/
int main()
{
ll n,m,l;
scanf("%lld %lld %lld",&n,&m,&l);
for(int i=1;i<=n*m;i++){
scanf("%lld",&val[i]);
}
sort(val+1,val+n*m+1);
int pos=lower_bound(val+1,val+n*m+1,val[1]+l+1)-val;
pos--;
//for(int i=1;i<=n*m;i++)printf("i:%d %lld\n",i,val[i]);
//printf("pos:%d\n",pos);
ll sum=0;
if(pos>=n*m){
for(int i=n*m-m+1;i>=1;i-=m)
sum+=val[i];
}
else{
int res=n*m-pos,cur=0;
for(int i=pos;i>=1;){
cur=0;
while(cur<m-1){
if(res)res--;
else i--;
cur++;
}
sum+=val[i];
i--;
}
}
if(pos<n)printf("0\n");
else printf("%lld\n",sum);
return 0;
}