#include <bits/stdc++.h>
using namespace std;

typedef long long ll;

#define rep(i,a,b) for(int i=a; i<b; i++)
#define all(x) (x).begin(), (x).end()

template<class T>bool chmax(T& a, const T& b) { if(a<b) {a=b; return 1;} return 0;}
template<class T>bool chmin(T& a, const T& b) { if(b<a) {a=b; return 1;} return 0;}

using pii = pair<int, int>;
using pll = pair<ll, ll>;

const ll MOD = 1000000007;
const ll INF = 1LL << 60;

int main(){
	int N; string S; cin >> N >> S;
	set<string> setT;
	rep(i,0,N-1){
		string T=S;
		T.replace(i,2,"BB");
		setT.insert(T);
	}
	cout << (int)setT.size() << endl;

}