#include<bits/stdc++.h>
using namespace std;
int n,t[26],ans;
string s,y="yuki";

bool dfs(string u,int d){
    if(u>y)return true;
    for(char c=(d<4?y[d]:'a');c<=(d?y[d-1]:'z');c++){
        if(t[c-'a']){
            t[c-'a']--;
            if(dfs(u+c,d+1))return true;
            t[c-'a']++;
        }
    }
    return false;
}

int main(){
    cin>>n>>s;
    while(n--)t[s[n]-'a']++;
    while(dfs("",0))ans++;
    cout<<ans<<endl;
}