#include <iostream>
#include <vector>
#include <cmath>
#include <map>
#include <set>
#include <iomanip>
#include <queue>
#include <algorithm>
#include <numeric>
#include <deque>
#include <complex>
#include <cassert>

using namespace std;
using ll = long long;

int main(){

    int N, ans=0;
    string S;
    cin >> N >> S;
    vector<vector<int>> v(3, vector<int>(3));

    for (int i=0; i<3*N; i++){
        if (S[i] == 'c') v[0][i%3]++;
        if (S[i] == 'o') v[1][i%3]++;
        if (S[i] == 'n') v[2][i%3]++;
    }

    for (int i=0; i<3; i++){
        ans += min({v[0][i%3], v[1][(i+1)%3], v[2][(i+2)%3]});
    }

    if (ans < N) cout << ans << endl;
    else{
        bool f=1;
        for (int i=0; i<N; i++){
            if (S[i*3] != 'c' || S[i*3+1] != 'o' || S[i*3+2] != 'n') f=0;
        }
        cout << (f ? ans : ans-1) << endl;
    }

    return 0;
}