#include<bits/stdc++.h>
#define int long long
using namespace std;
main(){
  ios::sync_with_stdio(false);
  int n; string s; cin>>n>>s;
  vector<int> t(n+1),f(n+1);
  vector a(n+1,vector<int>(26));
  iota(t.begin(),t.end(),0);
  for(int i=1;i<=n;i++){
    int x=a[t[i-1]][s[i-1]-97];
    if(x)t[i]=t[x-1],f[i]=f[x-1]+1;
    a[t[i]][s[i-1]-97]=i;
  }
  cout<<accumulate(f.begin(),f.end(),0ll)<<endl;
  return 0;
}