#include <bits/stdc++.h>
using namespace std;
template <class T>
inline T updmax(T& a, T b) {
  return a = max(a, b);
}
template <class T>
inline T updmin(T& a, T b) {
  return a = min(a, b);
}
class Solution {
 public:
  void solve() {
    long long n;
    string s;
    cin >> n >> s;
    vector<int> a(n, 0);
    vector<int> cnt(n, 0);
    int x = 0;
    long long ret = (n * (n + 1)) / 2 - n;
    for (int i = 0; i < n; i++) {
      a[i] = x;
      cnt[x]++;
      if (i == n - 1 || s[i] != s[i + 1]) x++;
    }
    if (x != 1) {
      for (int i = 0; i < x; i++) {
        if (i == 0 || i == x - 1)
          ret -= cnt[i];
        else
          ret -= 2 * cnt[i];
      }
      ret += x - 1;
    }
    cout << ret << "\n";
    return;
  };
};
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(nullptr);
  Solution solution;
  solution.solve();
  return 0;
}
