#include "bits/stdc++.h"
using namespace std;

int main() {
	vector<int> count(26);
	int N;
	cin >> N;
	string S;
	cin >> S;
	for (int i = 0; i < N; i++)
	{
		count[S[i] - 'a']++;
	}

	int ans = 0;

	for (int i = 0; i <= 'i' - 'a'; i++)
	{
		while (count['y' - 'a'] > 0 && count['u' - 'a'] > 0 && count['k' - 'a'] > 0 && count['i' - 'a'] > 0 && count[i] > 0 && (i != 'i' - 'a' || count[i] > 1)){
			count['y' - 'a']--;
			count['u' - 'a']--;
			count['k' - 'a']--;
			count['i' - 'a']--;
			count[i]--;
			ans++;
		}
	}

	for (int i = 'i' - 'a' + 1; i <= 'k' - 'a'; i++)
	{
		while (count['y' - 'a'] > 0 && count['u' - 'a'] > 0 && count['k' - 'a'] > 0 && count[i] > 0 && (i != 'k' - 'a' || count[i] > 1)){
			count['y' - 'a']--;
			count['u' - 'a']--;
			count['k' - 'a']--;
			count[i]--;
			ans++;
		}
	}


	for (int i = 'k' - 'a' + 1; i <= 'u' - 'a'; i++)
	{
		while (count['y' - 'a'] > 0 && count['u' - 'a'] > 0 && count[i] > 0 && (i != 'u' - 'a' || count[i] > 1)){
			count['y' - 'a']--;
			count['u' - 'a']--;
			count[i]--;
			ans++;
		}
	}


	for (int i = 'u' - 'a' + 1; i <= 'y' - 'a'; i++)
	{
		while (count['y' - 'a'] > 0 && count[i] > 0 && (i != 'y' - 'a' || count[i] > 1)){
			count['y' - 'a']--;
			count[i]--;
			ans++;
		}
	}

	for (int i = 'y' - 'a' + 1; i < 26; i++)
	{
		while (count[i] > 0){
			count[i]--;
			ans++;
		}
	}


	cout << ans << endl;
}