#include<cstdio>
int c,n,a,i,j;main(int d,char*s){scanf("%d%s",&n,s);for(;++c<=n;)for(i=n;i--;a+=!d)for(d=0,j=c;j--;)d+=s[i+j]^s[i+c-1-j];printf("%d\n",a);}