#include <bits/stdc++.h>
using namespace std;
const int N = 100010;
int ji,s[1100],la[1100],ans,u;
char c[N];
bool v[1100];
int main(){
    freopen("xxxx.in","r",stdin);
    freopen("xxxx.out","w",stdout);
    cin>>c+1;
    int l = strlen(c+1);
    for(int i = 1;i <= l;i++)v[c[i]] = 1;
    for(int i = 97;i <= 122;i++){
        ji = 0;
        if(!v[i])continue;
        memset(s,0,sizeof(s));
        memset(la,0,sizeof(la));
        for(int j = 1;j <= l;j++){
            u = int(c[j]);
            s[u]++;
            if(u == i){
                if((s[u] & 1) == 0)ans += ji;  
                else ji = 0,la[u] = j;  
            }
            else{
                if(s[u] & 1)ji++,la[u] = j;
                else if(la[u] > la[i]) ji--; 
            }
        }
    }
    printf("%d\n",ans);
    
    return 0;
    
}