code

#include <bits/stdc++.h>
using namespace std;
#define asp ""
#define aps ''
#define one 1
#define two 2
#define dif !=
typedef pair<int,int> ii;

int main(){

	ios::sync_with_stdio(0);
	cin.tie(0);

	vector<set<ii>> Number(2600005); // 26x10^5
	vector<bool> ocup(2600005);

	string s;
	cin >> s;

	for(int i=0;i<2600005;i++) ocup[i] = false;

	priority_queue<int,vector<int>,greater<int>> pq;

	for(int i=0;i<s.size();i++){
		int valor = s[i] - 'a' + 1;
		Number[valor].insert({i,i});  // push nos ponteiros
		if(!ocup[valor]){
			pq.push(valor);
			ocup[valor] = true;
		}
	}

	int cont = 0;

	while(!pq.empty()){

		int valor = pq.top();
		pq.pop();
		cont++;

		for(auto &pointer: Number[valor]){
			int novo;
			if(pointer.first - 1 >= 0){
				novo = valor + s[pointer.first - 1] - 'a' + 1;
				Number[novo].insert({pointer.first - 1,pointer.second});
				if(!ocup[novo]){
					pq.push(novo);
					ocup[novo] = true;
				}
			}
			if(pointer.second + 1 < s.size()){
				novo = valor + s[pointer.second + 1] - 'a' + 1;
				Number[novo].insert({pointer.first,pointer.second + 1});
				if(!ocup[novo]){
					pq.push(novo);
					ocup[novo] = true;
				}
			}
		}
	}

	cout << cont << endl;
}

// abbab
// adbbabdcdbcbacdabbaccdac