
#include<bits/stdc++.h>
using namespace std;
#define inf 1000000000
#define INF 1000000000000000
#define ll long long
#define ull unsigned long long
#define M (int)(1e9+7)
#define P pair<int,int>
#define PLL pair<ll,ll>
#define FOR(i,m,n) for(int i=(int)m;i<(int)n;i++)
#define RFOR(i,m,n) for(int i=(int)m;i>=(int)n;i--)
#define rep(i,n) FOR(i,0,n)
#define rrep(i,n) RFOR(i,n,0)
#define all(a) a.begin(),a.end()
#define IN(a,n) rep(i,n){ cin>>a[i]; }
const int vx[4] = {0,1,0,-1};
const int vy[4] = {1,0,-1,0};
#define PI 3.14159265
#define F first
#define S second
#define PB push_back
#define EB emplace_back
#define int ll
void init(){
  cin.tie(0);
  ios::sync_with_stdio(false);
}


main(){
  int n,k,q;
  cin>>n>>k>>q;
  vector<int> a(n);
  rep(i,n){
    cin>>a[i];
  }
  vector<int> ans;

  while(q--){
    int m=a.size();
    vector<P> res;
    rep(i,m){
      res.PB(P(a[i],i));
    }
    sort(all(res));
    //cout<<res[k-1].F<<' '<<endl;
    ans.PB(res[0].F);
    a.erase(a.begin()+res[0].S);
  }

  sort(all(ans));
  cout<<ans[ans.size()-1]-ans[0]<<endl;
}
