#include <bits/stdc++.h>
using namespace std;
char aa[100010];
int a[100010], used[100010];
int main()
{
	freopen("xxxx.in","r",stdin);
	freopen("xxxx.out","w",stdout);
	scanf("%s",aa+1);
	int len=strlen(aa+1),cnt; long long tot=0;
	for(register int i=1; i<=len; ++i)
	{
		a[i]=aa[i]-96;
	}
	for(register int i=1; i<=len; ++i)
	{
		if(used[a[i]]==0) {used[a[i]]=i;}
		else
		{
			cnt=0;
			for(register int j=used[a[i]]+1; j<i; ++j)
			{
				if(a[j]==0) {continue;}
				if(j>=i) break;
				++cnt;
			}
			tot+=cnt;
			a[used[a[i]]]=0; used[a[i]]=0; a[i]=0; 
		}
	}
	printf("%lld\n",tot);
	fclose(stdin);
	fclose(stdout);
	return 0;
}