#include <iostream>
#include <algorithm>
#include <functional>
#include <climits>
#include <cstring>
#include <string>
#define N_MAX 100000
#define USED 0
using namespace std;

int main()
{
	int N, ans = 0;
	char S[N_MAX + 1];
	cin >> N >> S;
	sort(S, S + N);
	bool find;

	//ごり押してみる ikuy
	for (int i = 0; i < N; ++i, find = true)
	{
		if (S[i] == 'y')
			for (int j = 0; j < N && find; ++j)
				if (S[j] == 'u' && S[j] < 'y')
					for (int k = 0; k < N && find; ++k)
						if (S[k] == 'k' && S[k] < 'u')
							for (int l = 0; l < N && find; ++l)
								if (S[l] == 'i' && S[l] < 'k')
									for (int m = 0; m < N && find; ++m)
									{
										if (m == i || m == j || m == k || m == l)
											continue;
										else if (S[m] != USED && S[m] < 'i')
										{
											S[m] = S[l] = S[k] = S[j] = S[i] = USED;
											++ans;
											find = false;
										}
									}
	}

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

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

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

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

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

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

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

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

	cout << ans;

	return 0;
}