func_code_string: #include <bits/stdc++.h>   using namespace std;   bool myfunction(int i, int j) { return (i < j); }   int main() {     int n, a, b, h;     cin >> n >> a >> b;     vector<int> myvector(n);     for (int i = 0; i < n; ++i) {       cin >> h;       myvector.at(i) = h;     }     sort(myvector.begin(), myvector.end(), myfunction);     cout << myvector.at(b) - myvector.at(b - 1) << endl;     return 0;   }   