Problem:
Score : 600 points

Problem Statement

You are given an integer sequence A of length N and an integer K.
You will perform the following operation on this sequence Q times:

Choose a contiguous subsequence of length K, then remove the smallest element among the K elements contained in the chosen subsequence (if there are multiple such elements, choose one of them as you like).

Let X and Y be the values of the largest and smallest element removed in the Q operations. You would like X-Y to be as small as possible.
Find the smallest possible value of X-Y when the Q operations are performed optimally.

Constraints

1 \leq N \leq 2000

1 \leq K \leq N

1 \leq Q \leq N-K+1

1 \leq A_i \leq 10^9

All values in input are integers.

Input

Input is given from Standard Input in the following format:

N K Q
A_1 A_2 ... A_N

Output

Print the smallest possible value of X-Y.

Sample Input 1

5 3 2
4 3 1 5 2

Sample Output 1

1

In the first operation, whichever contiguous subsequence of length 3 we choose, the minimum element in it is 1.
Thus, the first operation removes A_3=1 and now we have A=(4,3,5,2).
In the second operation, it is optimal to choose (A_2,A_3,A_4)=(3,5,2) as the contiguous subsequence of length 3 and remove A_4=2.
In this case, the largest element removed is 2, and the smallest is 1, so their difference is 2-1=1.

Sample Input 2

10 1 6
1 1 2 3 5 8 13 21 34 55

Sample Output 2

7

Sample Input 3

11 7 5
24979445 861648772 623690081 433933447 476190629 262703497 211047202 971407775 628894325 731963982 822804784

Sample Output 3

451211184

Solution in C++14 (GCC 5.4.1) (judge verdict: Wrong Answer)

#include<bits/stdc++.h>
using namespace std;

#define SPEED ios::sync_with_stdio(false); cin.tie(0); cout.tie(0)
#define read() 	        freopen("in.txt","r",stdin)
#define write()         freopen("out.txt","w",stdout)
#define sf(n) 	        scanf("%d",&n)
#define sfd(n)          scanf("%lf",&n)
#define sl(x)           scanf("%I64d",&x)
#define sfl(n) 	        scanf("%lld", &n)
#define sfc(n)          scanf(" %c",&n)
#define sful(n)         scanf("%ull",&n)
#define ull             unsigned long long int
#define endll           pf("\n")
#define pf              printf
#define pi              acos(-1.0)
#define eps 	        1e-10
#define mem(a,b)        memset(a,b,sizeof(a))
#define pb              push_back
#define xx              first
#define yy              second
#define pii             pair<int, int>
#define pll             pair<ll, ll>
#define MP make_pair
#define ll              long long
#define uniq(a)      a.erase(unique(a.begin(), a.end()), a.end())
#define cnd tree[idx]
#define lnd tree[idx<<1]
#define rnd tree[(idx<<1)+1]
#define lndp (idx<<1),(b),((b+e)>>1)
#define rndp ((idx<<1)+1),(((b+e)>>1)+1),(e)
#define inf 1999999999
#define MX 100005
#define mod 1000000007
#define var    int i,j,k,n,m,z=0,c=0,t,x,y,l,r,mid
//int dx[8]={0,0,1,1,-1,-1,1,-1};  //8 direction
//int dy[8]={1,-1,1,-1,1,-1,0,0};
//int dx[4]={1,-1,0,0};  //4 direction
//int dy[4]={0,0,1,-1};
int a[200005],b[200005],xr[200005];
map<int ,int > mp,st;
int main()
{
    var;
    cin>>n>>m>>k;
    for(i=0;i<n;i++)
    {
        cin>>a[i];
    }
    sort(a,a+n);
    c=a[k-1]-a[0];
    cout<<c<<endl;
}