#include<iostream>
#include<string>
#include<cstdio>
#include<vector>
#include<cmath>
#include<algorithm>
#include<functional>
#include<iomanip>
#include<queue>
#include<ciso646>
#include<random>
#include<map>
#include<set>
#include<bitset>
#include<stack>
#include<unordered_map>
#include<utility>
#include<cassert>
#include<complex>
#include<numeric>
using namespace std;

//#define int long long
typedef long long ll;

typedef unsigned long long ul;
typedef unsigned int ui;
constexpr ll mod = 1000000007;
const ll INF = mod * mod;
typedef pair<int, int>P;
#define stop char nyaa;cin>>nyaa;
#define rep(i,n) for(int i=0;i<n;i++)
#define per(i,n) for(int i=n-1;i>=0;i--)
#define Rep(i,sta,n) for(int i=sta;i<n;i++)
#define rep1(i,n) for(int i=1;i<=n;i++)
#define per1(i,n) for(int i=n;i>=1;i--)
#define Rep1(i,sta,n) for(int i=sta;i<=n;i++)
#define all(v) (v).begin(),(v).end()
typedef pair<ll, ll> LP;
typedef long double ld;
typedef pair<ld, ld> LDP;
const ld eps = 1e-12;
const ld pi = acos(-1.0);

ll mod_pow(ll x, ll n, ll m) {
	ll res = 1;
	while (n) {
		if (n & 1)res = res * x % m;
		x = x * x % m; n >>= 1;
	}
	return res;
}
struct modint {
	ll n;
	modint() :n(0) { ; }
	modint(ll m) :n(m) {
		if (n >= mod)n %= mod;
		else if (n < 0)n = (n % mod + mod) % mod;
	}
	operator int() { return n; }
};
bool operator==(modint a, modint b) { return a.n == b.n; }
modint operator+=(modint& a, modint b) { a.n += b.n; if (a.n >= mod)a.n -= mod; return a; }
modint operator-=(modint& a, modint b) { a.n -= b.n; if (a.n < 0)a.n += mod; return a; }
modint operator*=(modint& a, modint b) { a.n = ((ll)a.n * b.n) % mod; return a; }
modint operator+(modint a, modint b) { return a += b; }
modint operator-(modint a, modint b) { return a -= b; }
modint operator*(modint a, modint b) { return a *= b; }
modint operator^(modint a, int n) {
	if (n == 0)return modint(1);
	modint res = (a * a) ^ (n / 2);
	if (n % 2)res = res * a;
	return res;
}

ll inv(ll a, ll p) {
	return (a == 1 ? 1 : (1 - p * inv(p % a, a)) / a + p);
}
modint operator/(modint a, modint b) { return a * modint(inv(b, mod)); }

const int max_n = 1 << 17;
modint fact[max_n], factinv[max_n];
void init_f() {
	fact[0] = modint(1);
	for (int i = 0; i < max_n - 1; i++) {
		fact[i + 1] = fact[i] * modint(i + 1);
	}
	factinv[max_n - 1] = modint(1) / fact[max_n - 1];
	for (int i = max_n - 2; i >= 0; i--) {
		factinv[i] = factinv[i + 1] * modint(i + 1);
	}
}
modint comb(int a, int b) {
	if (a < 0 || b < 0 || a < b)return 0;
	return fact[a] * factinv[b] * factinv[a - b];
}

void solve() {
	int alf[26] = {};
	int n; cin >> n;
	string s; cin >> s;
	rep(i, n)alf[s[i] - 'a']++;
	int ans = 0;
	ans += alf[25]; alf[25] = 0;
	int cy = 'y' - 'a';
	int cu = 'u' - 'a';
	int ck = 'k' - 'a';
	int ci = 'i' - 'a';
	int num = 0;
	Rep(i,cu+1,cy) {
		num += alf[i];
	}
	if (num > alf[cy]) {
		ans += alf[cy]; alf[cy] = 0;
	}
	else {
		ans += num;
		alf[cy] -= num;

		num = 0;
		Rep(i, ck + 1, cu)num += alf[i];

		int ex = min(alf[cy], alf[cu]);
		if (num>ex) {
			ans += ex;
			alf[cy] -= ex;
			alf[cu] -= ex;
		}
		else {
			ans += num;
			alf[cy] -= num;
			alf[cu] -= num;

			num = 0;
			Rep(i, ci + 1, ck)num += alf[i];
			ex = min({ alf[cy],alf[cu],alf[ck] });
			if (num > ex) {
				ans += ex;
				alf[cy] -= ex;
				alf[cu] -= ex;
				alf[ck] -= ex;
			}
			else {
				ans += num;
				alf[cy] -= num;
				alf[cu] -= num;
				alf[ck] -= num;

				num = 0;
				rep(i, ci)num += alf[i];
				ex = min({ alf[cy],alf[cu],alf[ck],alf[ci] });
				int mi = min(num, ex);
				ans += mi;
				alf[cy] -= mi;
				alf[cu] -= mi;
				alf[ck] -= mi;
				alf[ci] -= mi;
				//yulii
				int d = min({ alf[cy],alf[cu],alf[ck],alf[ci] / 2 });
				ans += d;
				alf[cy] -= d;
				alf[cu] -= d;
				alf[ck] -= d;
				alf[ci] -= 2*d;



				//yukk
				d = min({ alf[cy],alf[cu],alf[ck] / 2 });
				ans += d;
				alf[cy] -= d;
				alf[cu] -= d;
				alf[ck] -= 2 * d;
			}




			//yuu
			int d = min(alf[cy], alf[cu] / 2);
			ans += d;
			alf[cy] -= d;
			alf[cu] -= 2 * d;
		}



		//yy
		ans += alf[cy] / 2;
	}
	cout << ans << "\n";
}




signed main() {
	ios::sync_with_stdio(false);
	cin.tie(0);
	cout << fixed << setprecision(10);
	//init_f();
	//int t; cin >> t; rep(i, t)
	solve();
	return 0;
}