#include <bits/stdc++.h>
using namespace std;
map<char, int> mp;
char t[27];
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  long long n, mx = 0, ans = 0, f, f1;
  string ch;
  cin >> n;
  for (int i = 0; i < n; i++) {
    cin >> ch;
    t[ch[0] - 'a']++;
  }
  for (int i = 0; i < 27; i++) {
    mx = t[i];
    f = mx / 2;
    if (mx % 2 == 0)
      f1 = mx / 2;
    else
      f1 = mx / 2 + 1;
    ans += (f1 * (f1 - 1) / 2) + (f * (f - 1) / 2);
  }
  cout << ans;
  return 0;
}
