题解 | #字符个数统计#

#include <iostream>
#include <string>
#include <unordered_set>

int main(int argc, char* argv[]){
    std::string str;
    std::cin >> str;
    std::unordered_set<char> occ;
    for(char c : str){
        if(c >= 0 && c <= 127){
            occ.insert(c);
        }
    }
    std::cout << occ.size() << std::endl;
    return 0;
}