#include<cstdio>
#include<iostream>
#include<string>
#include<cstring>
using namespace std;
string a;
char b[100001];
int main()
{
	freopen("xxxx.in","r",stdin);
	freopen("xxxx.out","w",stdout);
	getline(cin,a);
	memset(b,1,sizeof(b));
	int ans=0,i=1;
    for(i=1;i<a.length();i++)
    {
    	int t=i;
    	for(int j=0;j<i;j++)
    	{
    		if(b[j]==0) continue;
			else
			{
				
					if(a[i]==a[j]) 
				{
					b[i]=b[j]=0;
					int n=i,m=j;
					while(n>m)
		    		{
			    		ans+=b[m];
			    		
			    		m++;	
					}	
				}
				else continue;
			}
    	
    		
 		}
    	
    	
	}
	printf("%d",ans);
	return 0;
	
}