#include<bits/stdc++.h>
using namespace std;
using ui=unsigned int;
using uli=unsigned long long int;
istream& fin=cin;
ostream& fout=cout;
int main(void){
    ios::sync_with_stdio(false),cin.tie(nullptr),cout.tie(nullptr);
    size_t n;fin>>n;
    vector<unsigned char> s(n);
    for (unsigned char& i:s){
        char c;fin>>c;
        i=c-'a';
    }
    vector<size_t> f(n+1);vector<ui> g(n+1);f[0]=-1,g[0]=0;
    for (size_t i=0;i<n;++i){
        for (f[i+1]=i;~f[i+1];f[i+1]=f[f[i+1]])
            if (f[i+1]&&s[f[i+1]-1]==s[i]){
                --f[i+1];
                break;
            }
        if (~f[i+1]) g[i+1]=g[f[i+1]]+1;
    }
    fout<<accumulate(g.begin(),g.end(),uli(0));
    return 0;
}