Codeforces Round #479 (Div. 3) 977C. Less or Equal Solution

 Problem Link :  https://codeforces.com/problemset/problem/977/C

 Solution in C++:

///La ilaha illellahu muhammadur rasulullah

///******Bismillahir-Rahmanir-Rahim******///

///Abul Hasnat  Tonmoy

///Department of CSE,23rd batch

///Islamic University,Bangladesh

#include <bits/stdc++.h>

using namespace std;

int main()

{

    long long n,k,i,ans=-1;

    cin>>n>>k;

    int a[n+9];

    a[0]=1;

    a[n+1]=1000000001;

    for(i=1; i<=n; i++)

        cin>>a[i];

    sort(a,a+n+2);

    if(a[k]==a[k+1])

        cout<<"-1"<<endl;

    else

        cout<<a[k]<<endl;

}