pairs in arrays elements

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

int countFreq(int ar[], int n)
{

	vector<bool> visited(n, false);

	int ans;
	int div, result=0;

	map<int, int> mp;


    for (int i = 0; i < n; i++) {

        if (visited[i] == true)
            continue;

        int count = 1;
        for (int j = i + 1; j < n; j++) {
            if (ar[i] == ar[j]) {
                visited[j] = true;
                count++;
            }
        }
         mp.insert({ ar[i] , count });


    }

    map<int, int>::iterator itr;
    for (itr = mp.begin(); itr != mp.end(); ++itr) {
             ans = itr->first;
             if(ans>=2)
             {
                 div = ans/2;
             }
             result = result + div;
    }

    return result;

}

int main()
{
    int pairs;
	int ar[] = { 10, 20, 20, 10, 10, 20, 5, 20 };
	int n = sizeof(ar) / sizeof(ar[0]);
	pairs = countFreq(ar, n);
	cout<<pairs;
	return 0;
}