/*
ID: tiankonguse
TASK: game
LANG: C++
CONTEST: CSP-S 2023
OJ: https://qoj.ac/problem/7814
*/
#define TASK "lock"

#include <bits/stdc++.h>

using namespace std;
typedef long long ll;

const int N = 2 * 10e6 + 10;
char str[N];
void InitIO() {
  // #ifndef USACO_LOCAL_JUDGE
  //   freopen(TASK ".in", "r", stdin);
  //   freopen(TASK ".out", "w", stdout);
  // #endif
}

/*

*/
void Solver() {  //
  ll n;
  scanf("%lld%s", &n, str);
  unordered_map<ll, ll> h;
  h[0] = 1;
  ll pre = 0;

  ll ans = 0;
  for (int i = 0; i < n; i++) {
    const ll v = str[i] - 'a';
    pre = pre ^ (1 << v);
    ans += h[pre];
    h[pre]++;
  }
  printf("%lld\n", ans);
}

int main() {
  InitIO();
  Solver();
  return 0;
}
/*
8
accabccb

枚举每个
*/