#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
#include <queue>
#include <atcoder/modint>

using namespace std;
using i32 = int32_t;
using u32 = uint32_t;
using i64 = int64_t;
using u64 = uint64_t;
#define rep(i,n) for(int i=0; i<(int)(n); i++)

using Modint = atcoder::static_modint<998244353>;


int main(){
rep(t,5){
    int C[3][3] = {};
    string con = "con";
    int N; cin >> N;
    N *= 3;
    string S; cin >> S;
    rep(i,N){
        auto p = con.find(S[i]);
        if(p != string::npos) C[i%3][p]++;
    }
    int ans = 0;
    int q = N;
    rep(t,3){
        int con = min({ q/3, C[(0+t)%3][0], C[(1+t)%3][1], C[(2+t)%3][2] });
        ans += con;
        q -= con * 3 + 1;
    }
    cout << ans << '\n';
}
    return 0;
}


struct ios_do_not_sync{
    ios_do_not_sync(){
        std::ios::sync_with_stdio(false);
        std::cin.tie(nullptr);
    }
} ios_do_not_sync_instance;