Merge sort Employee ass

#include <iostream>
using namespace std;

class merg{
    int arr[15] = {};
public:
    void input(int n){
        for(int i = 0; i < n; i++){
            cout << "Enter salary" << i + 1 << ": " << endl;
            cin >> arr[i];
        }
    }

    void merge(int l, int m, int r) {
       int i, j, k, nl, nr;
       nl = m-l+1; nr = r-m;
       int leftarr[nl], rightarr[nr];

       for(i = 0; i<nl; i++)
          leftarr[i] = arr[l+i];
       for(j = 0; j<nr; j++)
          rightarr[j] = arr[m+1+j];

       i = 0; j = 0; k = l;
       while(i < nl && j<nr) {
          if(leftarr[i] <= rightarr[j]) {
             arr[k] = leftarr[i];
             i++;
          }else{
             arr[k] = rightarr[j];
             j++;
          }
          k++;
       }

       while(i<nl) {
          arr[k] = leftarr[i];
          i++; k++;
       }
       while(j<nr) {
          arr[k] = rightarr[j];
          j++; k++;
       }
    }

    void mergesort(int start, int end){
        if(start < end){
            int middle = (start + end)/2;
            mergesort(start, middle);
            mergesort(middle + 1, end);
            merge(start, middle, end);
        }
        else{
            return;
        }
    }

    void display(int n){
        if(n < 5){
            cout << "Top " << n << " employee salary: " << endl;
            for(int i = n - 1; i >= 0; i--){
                cout << " " << arr[i];
            }
        }
        else{
            cout << "Top 5 employee salary: " << endl;
            for(int i = n - 1; i > n - 6; i--){
                cout << " " << arr[i];
            }
        }
    }
};

int main(){
    merg n;
    int num = 0;
    cout << "Enter no of employees (<15): " << endl;
    cin >> num;
    n.input(num);
    n.mergesort(0, num-1);
    n.display(num);
    return 0;
}