#include <stdio.h>
#include <atcoder/all>
#include <bits/stdc++.h>
using namespace std;
using namespace atcoder;
using mint = modint998244353;
#define rep(i,n) for (int i = 0; i < (n); ++i)
#define Inf32 1000000001
#define Inf64 4000000000000000001



int main(){
	
	int N;
	cin>>N;
	
	string S;
	cin>>S;
	
	string s = "con";
	vector<int> cnt(3,0);
	int ans = 0;
	rep(i,3){
		vector<int> c(3,0);
		rep(j,S.size()){
			if(s[(j+3-i)%3]==S[j]){
				c[(j+3-i)%3]++;
			}
		}
		cnt[i] = min({c[0],c[1],c[2]});
	}
	
	vector<int> t(3);
	rep(i,3)t[i] = i;
	
	do{
		int cur = 0;
		int sum = 0;
		rep(i,3){
			while(cur%3!=t[i])cur++;
			int cc = cnt[t[i]];
			while(cc!=0 && cur+3<=3*N){
				cur+=3;
				sum++;
				cc--;
			}
		}
		ans = max(ans,sum);
	}
	while(next_permutation(t.begin(),t.end()));
	
	cout<<ans<<endl;
	return 0;
}