#include<cstdio>
#include<iostream>
#include<cstring>
#include<cstdlib>
#include<algorithm>
#include<cmath>
using namespace std;
typedef long long LL;
const int _=1e2;
const int maxn=3*1e5+_;
const int maxc=2*26+10;
const int hmod=8388607;LL Bin[maxn];
struct Hash
{int first[hmod],last[hmod],nxt[maxn];int len,c[maxn];LL d[maxn];void insert(LL k){int x=k&hmod;for(int i=first[x];i;i=nxt[i])if(d[i]==k){c[i]++;return ;}int now=++len;if(first[x]==0)first[x]=last[x]=now;else nxt[last[x]]=now,last[x]=now;d[now]=k,c[now]++;}   int getsum(LL k){int x=k&hmod;for(int i=first[x];i;i=nxt[i])if(d[i]==k)return c[i];return 0;}
}H;int n,a[maxn];bool v[maxc];
char ss[maxn];
int main()
{Bin[0]=1;for(int i=1;i<maxc;i++)Bin[i]=Bin[i-1]*2;scanf("%d%s",&n,ss+1);LL ans=0; LL sum=0;H.insert(sum);for(int i=1;i<=n;i++){if('a'<=ss[i]&&ss[i]<='z')a[i]=ss[i]-'a'+1;else a[i]=ss[i]-'A'+27;v[a[i]]=true;sum^=Bin[a[i]-1];ans=ans+H.getsum(sum);for(int j=1;j<=52;j++)if(v[j])ans=ans+H.getsum(sum^Bin[j-1]);H.insert(sum);}printf("%lld\n",ans);return 0;
}