#include<bits/stdc++.h>
using namespace std;
const int N=510000;
char a[N], s1[2*N], s2[2*N];
int d[2*N], n;
void get_d()
{
    s1[0]='$'; s1[1]='#';
    for(int i=1; i<=n; i++) {
        s1[2*i] = a[i];
        s2[2*i] = a[i] ^ 1;
        s1[2*i+1] = s2[2*i+1] = '#';
    }
    n = 2*n + 1;
    memset(d, 0, sizeof(d)); d[1] = 1;
    for(int i=2, L=1, R=1; i<=n; i++) {
        if(i <= R) d[i] = min(d[R - i + L], R - i + 1);
        while(s1[i - d[i]] == s2[i + d[i]]) d[i]++;
        if(i + d[i] - 1 > R) {
            L = i - d[i] + 1;
            R = i + d[i] - 1;
        }
    }
}
int main()
{
    scanf("%d%s", &n, a + 1);
    get_d();
    long long ans = 0;
    for(int i=1; i<=n; i++) ans += (d[i] - 1)/2;
    printf("%lld\n", ans);
    return 0;
}

#include<bits/stdc++.h>
using namespace std;
const int N=510000;
char a[N],s1[2*N],s2[2*N];
int d[2*N],n;
void get_d()
{
	s1[0]=s2[0]='$';s1[1]=s2[1]='#';
	for(int i=1;i<=n;i++)s1[2*i]=a[i],s2[2*i]=a[i]^1,s1[2*i+1]=s2[2*i+1]='#';
	n=2*n+1;
	memset(d,0,sizeof(d));d[1]=1;
	for(int i=2,L=1,R=1;i<=n;i++)
	{
		if(i<=R) d[i]=min(d[R-i+L],R-i+1);
		while( s1[i-d[i]]==s2[i+d[i]])  d[i]++;
		if(i+d[i]-1>R) L=i-d[i]+1,R=i+d[i]-1;
	}
}
int main()
{
    scanf("%d%s",&n,a+1);
    get_d();
    long long  ans=0;
    for(int i=1;i<=n;i++) ans+=(d[i]-1)/2;
    printf("%lld\n",ans);
    return 0;
}