#include <bits/stdc++.h>
using namespace std;
const long long M = 200005;
const double pi = 3.141592653589793238463;
long long modularExponentiation(long long x, long long n, long long M) {
  long long result = 1;
  while (n > 0) {
    if (n % 2 == 1) result = (result * x) % M;
    x = (x * x) % M;
    n = n / 2;
  }
  return result;
}
long long fast_exp(long long x, long long n) {
  long long ans = 1;
  while (n) {
    if (n & 1) ans *= x;
    n = n >> 1;
    x = x * x;
  }
  return ans;
}
bool sortbysec(const pair<long long, long long> &a,
               const pair<long long, long long> &b) {
  return (a.second < b.second);
}
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(NULL);
  cout.tie(NULL);
  ;
  long long n, j = 0;
  cin >> n;
  string s;
  cin >> s;
  long long ans = n * (n - 1) / 2;
  for (long long i = 0; i < n; i++) {
    j = i + 1;
    while (j < n and s[i] == s[j]) j++;
    j--;
    if (i > 0) ans -= j - i + 1;
    if (j < n - 1) ans -= j - i + 1;
    ans++;
    i = j;
  }
  cout << ans - 1;
}
