#include <bits/stdc++.h>
using namespace std; 
typedef long long i64; 

int n; 
int f[2000005], lst[2000005]; 
char a[2000005]; 

int main(void) {
    cin >> n >> a + 1; memset(lst, 0xff, sizeof lst); 
    for (int i = 1; i <= n; ++i) {
        if (a[i] == a[i - 1]) lst[i] = i - 1; 
        else {
            int j = i - 1; 
            while (lst[j] != -1) {
                j = lst[j] - 1; 
                if (a[i] == a[j]) { lst[i] = j; break; }
            }
        }
        if (lst[i] != -1) f[i] = f[lst[i] - 1] + 1; 
    }
    i64 ans = 0; 
    for (int i = 1; i <= n; ++i) ans += f[i]; 
    cout << ans << "\n"; 
    return 0; 
}