import java.util.*;
import java.io.*;
import java.math.*;
import java.awt.geom.*;

import static java.lang.Math.*;

public class Solution implements Runnable {

    public void solve() throws Exception {
        int n = sc.nextInt();
        String str = in.readLine();

        int[] balance = new int[n + 1];
        for (int i = 0; i < n; i++) {
            if (str.charAt(i) == 'a') {
                balance[i + 1] = balance[i] + 1;
            } else {
                balance[i + 1] = balance[i] - 1;
            }
        }

        Arrays.sort(balance);

        long ans = 0;
        for (int i = 0; i <= n; ) {
            int j = i;
            while (j <= n && balance[j] == balance[i]) {
                j++;
            }
            long cnt = j - i;
            ans += cnt * (cnt - 1) / 2;
            i = j;
        }

        out.println(ans);
    }

    static Throwable uncaught;

    BufferedReader in;
    FastScanner sc;
    PrintWriter out;

    @Override
    public void run() {
        try {
            in = new BufferedReader(new InputStreamReader(System.in));
            out = new PrintWriter(System.out);
            sc = new FastScanner(in);
            solve();
        } catch (Throwable uncaught) {
            Solution.uncaught = uncaught;
        } finally {
            out.close();
        }
    }

    public static void main(String[] args) throws Throwable {
        Thread thread = new Thread(null, new Solution(), "", (1 << 26));
        thread.start();
        thread.join();
        if (Solution.uncaught != null) {
            throw Solution.uncaught;
        }
    }

}

class FastScanner {

    BufferedReader in;
    StringTokenizer st;

    public FastScanner(BufferedReader in) {
        this.in = in;
    }

    public String nextToken() throws Exception {
        while (st == null || !st.hasMoreTokens()) {
            st = new StringTokenizer(in.readLine());
        }
        return st.nextToken();
    }

    public int nextInt() throws Exception {
        return Integer.parseInt(nextToken());
    }

    public long nextLong() throws Exception {
        return Long.parseLong(nextToken());
    }

    public double nextDouble() throws Exception {
        return Double.parseDouble(nextToken());
    }

}