#include <iostream>
#include <vector>
#include <functional>
#include <chrono>
#include <random>
#include <map>

using namespace std;

const int N = 2e6 + 3;

int n, prefix[N], a[N];
string s;

int get_sum(int l, int r){
    if(l > r) return 0;
    return prefix[r] - prefix[l - 1];
}

bool check(int x){
    int l = 1, r = 0;
    int cnt = 0;
    while(r <= 2 * n - 1){
        if(l > r){
            ++r;
        }
        else if(r - l + 1 < n || get_sum(l, r) < x){
            ++r;
        }
        else if(get_sum(l, r) > x){
            ++l;
        }
        else if(r != 2 * n - 1 && a[r + 1] == 0){
            ++r;
        }
        else if(l < r){
            ++l;
        }
        else if(r != 2 * n - 1){
            ++r;
        }
        else{
            break;
        }

        if(r > 2 * n - 1) break;
        if(r - l + 1 >= n && get_sum(l, r) == x){
            ++cnt;
            if(cnt >= n) return true;
        }
    }
    return false;
}

int main(){
    ios::sync_with_stdio(false);
    cin.tie(NULL);

    cin >> n >> s;
    // cin >> n;
    mt19937 mt(chrono::steady_clock::now().time_since_epoch().count());
    for(int i = 1; i <= 2 * n - 1; ++i){
        a[i] = s[i - 1] == 'W';
        // a[i] = 1;
        prefix[i] = prefix[i - 1] + a[i];
    }
    // s.resize(2 * n - 1);

    vector<int> mp(2 * n);
    
    for(int i = 1; i <= n; ++i){
        int l = mt() % s.size() + 1;
        int r = mt() % s.size() + 1;
        if(l > r) swap(l, r);

        if(r - l + 1 < n){
            --i;
            continue;
        }

        if(get_sum(l, r) > n) continue;
        mp[get_sum(l, r)]++;
    }

    vector<pair<int, int>> v;
    for(int i = 0; i <= n; ++i){
        if(mp[i]){
            v.push_back({mp[i], i});
        }
    }
    v.push_back({n, 0});
    v.push_back({n, n});
    v.push_back({n, get_sum(1, n)});
    v.push_back({n, get_sum(n, 2 * n - 1)});

    int ans;
    while(true){
        auto it = max_element(v.begin(), v.end());
        // cout << it->second << " cand" << endl;
        if(check(it->second)){
            ans = it->second;
            break;
        }
        swap(*it, v.back());
        v.pop_back();
    }

    cout << ans << "\n";
}