#include<bits/stdc++.h>
using namespace std;
#define int long long	
int rd() {
	int x = 0, w = 1;
	char ch = 0;
	while (ch < '0' || ch > '9') {
		if (ch == '-') w = -1;
		ch = getchar();
	}
	while (ch >= '0' && ch <= '9') {
		x = x * 10 + (ch - '0');
		ch = getchar();
	}
	return x * w;
}

void wt(int x) {
	static int sta[35];
	int f = 1;
	if(x < 0) f = -1,x *= f;
	int top = 0;
	do {
		sta[top++] = x % 10, x /= 10;
	} while (x);
	if(f == -1) putchar('-');
	while (top) putchar(sta[--top] + 48);
}
const int N = 2e6 + 5;
int n;
char s[N];
int dp[N],to[N],f[N][26],ans;

signed main() {
	scanf("%lld",&n);
	scanf("%s",s + 1);
	for(int i = 1;i<=n;i++) {
		to[i] = i;
		int x;
		x = f[to[i - 1]][s[i] - 'a'];
		if(x) to[i] = to[x - 1],dp[i] = dp[x - 1] + 1;
		f[to[i]][s[i] - 'a'] = i;
		ans += dp[i]; 
	}
	wt(ans);
	return 0;
}