#include <iostream>
#include <algorithm>
#include <climits>
#include <cstring>
#include <string>
#define N_MAX 10000
using namespace std;

int main()
{
	int N, ans = 0;
	char S[N_MAX];
	cin >> N >> S;

	//ごり押してみる
	for (int i = 0; i < N; ++i)
		if (S[i] > 'y')
		{
			++ans;
			S[i] = 0;
		}

	for (int i = 0; i < N; ++i)
		if (S[i] == 'y')
			for (int j = 0; j < N; ++j)
				if (j == i)
					continue;
				else 	if (S[j] > 'u')
				{
					++ans;
					S[j] = S[i] = 0;
				}

	for (int i = 0; i < N; ++i)
		if (S[i] == 'y')
			for (int j = 0; j < N; ++j)
				if (S[j] == 'u')
					for (int k = 0; k < N; ++k)
						if (k == i || k == j)
							continue;
						else if (S[k] > 'k')
						{
							++ans;
							S[k] = S[j] = S[i] = 0;
						}



	for (int i = 0; i < N; ++i)
		if (S[i] == 'y')
			for (int j = 0; j < N; ++j)
				if (S[j] == 'u')
					for (int k = 0; k < N; ++k)
						if (S[k] == 'k')
							for (int l = 0; l < N; ++l)
								if (l == i || l == j || l == k)
									continue;
								else if (S[l] > 'i')
								{
									++ans;
									S[l] = S[k] = S[j] = S[i] = 0;
								}

	for (int i = 0; i < N; ++i)
		if (S[i] == 'y')
			for (int j = 0; j < N; ++j)
				if (S[j] == 'u')
					for (int k = 0; k < N; ++k)
						if (S[k] == 'k')
							for (int l = 0; l < N; ++l)
								if (S[l] == 'i')
									for (int m = 0; m < N; ++m)
										if (m == i || m == j || m == k || m == l)
											continue;
										else if (S[m])
										{
											S[m] = S[l] = S[k] = S[j] = S[i] = 0;
											++ans;
										}


	cout << ans;

	return 0;
}