#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;
const int maxn=100005;
int n,np=0,last[30];
bool vis[30];
char s[maxn];
struct data
{
	int x,y;
	friend bool operator<(data a,data b)
	{
		return a.x<b.x;
	}
}a[maxn];
int main()
{
	freopen("xxxx.in","r",stdin);
	freopen("xxxx.out","w",stdout);
	memset(vis,0,sizeof(vis));
    scanf("%s",&s[1]);
    n=strlen(&s[1]);
	for(int i=1;i<=n;i++)
	{
		s[i]-='a';
		if(vis[s[i]])vis[s[i]]=0,a[last[s[i]]].y=i;
		else vis[s[i]]=1,last[s[i]]=++np,a[np].x=i;
	}
	n=np;
	sort(a+1,a+n+1);
	int ans=0;
	for(int i=1;i<=n;i++)
	{
		for(int j=i+1;j<=n&&a[j].x<a[i].y;j++)
		if(a[j].y>a[i].y)ans++;
	}
	cout<<ans;
	return 0;
}