sort/권영기

#include<iostream>
#include<algorithm>
#include<vector>
using namespace std;
vector < vector <int> > number;
int cmp(int s, int w)
{
	return s<w;
}
int main(void)
{
	int n, i, j, ans = 0;

	cin>>n;
	number.resize(2);
	number[0].resize(n + 5), number[1].resize(n + 5);
	for(i = 0; i<n; i++){
		cin>>number[0][i];
		number[1][i] = number[0][i];
	}
	sort(number[1].begin(), number[1].begin() + n, cmp);
	for(i = 0; i<n; i++){
		for(j = i + 1; j<n; j++){
			if(number[0][i] != number[1][i] && number[0][j] != number[1][j] && number[0][i] == number[1][j] && number[1][i] == number[0][j]){
				number[0][i] = number[1][i];
				number[0][j] = number[1][j];
				ans++;
				break;
			}
		}
	}

	for(i = 0; i<n; i++){
		for(j = i + 1; j<n; j++){
			if(number[0][i] != number[1][i] && number[0][j] != number[1][j] && number[1][i] == number[0][j]){
				number[0][j] = number[0][i];
				number[0][i] = number[1][i];
				ans++;
				break;
			}
		}
	}
	cout<<ans;
	return 0;
}