#include <bits/stdc++.h>
using namespace std;
int n,d[9],z,x,o;
char y[4] = {'y','u','k','i'};
string s;
int main(){cin>>n>>s;for(int i=0; s.size()>i;i++){o=1;for(int j=0;8>j;j+=2){if(s[i]>=y[j/2]){o=0;d[j+(s[i]==y[j/2])]++;break;}}if(o)d[8]++;}reverse(d,d+9);z = (d[1]>d[0]?d[0]+(d[1]-d[0])/2:d[1]);for(int i = 2;7>i;i+=2){x = min(d[i],d[i+1]);if(d[i+1]>d[i]){d[i+1]-=d[i];x+=min(d[i+1],z);if(d[i+1]>z)x+=(d[i+1]-z)/2;}z=x;}cout <<z+d[8]<< endl;}