#include<iostream>
#include<cstring>
#include<cstdio>
#define lowbit(i) ((i)&(-i))
using namespace std;
const int maxn = 100000;
int first[maxn];
int A[maxn];
int c[maxn];
void update(int x,int v){
    for(int i = x;i < maxn;i += lowbit(i)){
        c[i] += v;
        }
    }
int getsum(int x){
    int sum = 0;
    for(int i = x;i > 0;i -= lowbit(i)){
        sum += c[i];
        }
    return sum;
    }
    
int main(){
	freopen("xxxx.in","r",stdin);
	freopen("xxxx.out","w",stdout);
	char c[maxn];
	cin>>c;
	int len = strlen(c);
	int cnt;
	for(int i = 1;i <= len;i++){
		int tb = c[i - 1] - 'a';
		if(first[tb] == 0){
			first[tb] = i;
			update(i,1);
			}
		else{
			cnt += (getsum(i - 1) - getsum(first[tb]));
			update(first[tb],-1);
			first[tb] = 0;
			}
		}
	cout<<cnt<<endl;
	fclose(stdin);
	fclose(stdout);
	return 0;
	}