lenar
- #include <iostream>
- #include <set>
-
- using namespace std;
-
- int main() {
- string s;
- bool name = true;
- getline(cin, s);
- set<char> alph;
- for (int i = 0; i < 10; ++ i) {
- alph.insert(char('0' + i));
- }
- for (int i = 0; i < 26; ++ i) {
- alph.insert(char('a' + i));
- alph.insert(char('A' + i));
- alph.insert(char('_'));
- }
- if ((s[0] >= '0' && s[0] <= '9')) {
- cout << "NO";
- return 0;
- }
- for (int i = 0; i < s.size(); ++ i) {
- if (! (s[i] >= 'a' && s[i] <= 'z') && ! (s[i] >= 'A' && s[i] <= 'Z') && s[i] != '_' && !(s[i] >= '0' && s[i] <= '9')) {
- cout << "NO";
- return 0;
- }
- }
- if (name) {
- cout << "YES";
- }
- return 0;
- }