#include <iostream>
#include <string>
#include <numeric>
#include <algorithm>
int main()
{
std::string nr;
std::cin >> nr;
std::cout << std::accumulate(std::begin(nr), std::end(nr), 0, [nr] (int init, char cfr) {
return init + (std::count(std::begin(nr), std::end(nr), cfr) == 1);
});
}
