#include<bits/stdc++.h>
using namespace std;
char s[100005];
int ans,sum[1005],a[1005],begin[1005];
int main(){
	freopen("xxxx.in","r",stdin);
	freopen("xxxx.out","w",stdout);
	gets(s+1);
	int n=strlen(s+1);
	for(int i=1;i<=n;++i){
		a[s[i]]++;a[s[i]]%=2;
		if(a[s[i]]==1){
			begin[s[i]]=i;
			for(int j=97;j<=122;++j){if(j==s[i])continue;if(a[j])sum[j]++;}
		}
		else {
			ans+=sum[s[i]];sum[s[i]]=0;
			for(int j=97;j<=122;++j)if(a[j]==1&&begin[j]<begin[s[i]])sum[j]--;
			begin[s[i]]=0;
		}
	}
	printf("%d",ans);
	return 0;
}