tuple <string, int, bool> add_new_digit(string s, string ip, int i, int num_count, bool ip_is_valid) {
    if (isdigit(s[i])) {
        ip.push_back(s[i]);
        num_count++;
    }
    if (!isdigit(s[i]) && s[i] != '.') {
        ip_is_valid = false;
    }
    return make_tuple(ip, num_count, ip_is_valid);
}

tuple <string, int, int, bool> check_number_is_valid(string s, string ip, int i, int num_count, int dots_count, bool ip_is_valid) {
    if (s[i] == '.' || i == s.length() - 1) {
        if (s[i] == '.') {
            dots_count++;
        }
        if (num_count == 0 || num_count > 3) {
            ip_is_valid = false;
        }
        else {
            int number = stoi(ip);
            if (number > 255) {
                ip_is_valid = false;
            }
        }
        num_count = 0;
        ip.clear();
    }
    return make_tuple(ip, num_count, dots_count, ip_is_valid);
}

int task7 () {
    string s;
    getline(cin, s);
    string ip, valid_ip = "YES";
    bool ip_is_valid = true;
    int num_count = 0, dots_count = 0;
    if (s.length() < 7) {
        ip_is_valid = false;
    }
    for (int i = 0; i < s.length(); i++) {
        tie(ip, num_count, ip_is_valid) = add_new_digit(s, ip, i, num_count, ip_is_valid);
        if (!ip_is_valid) {
            break;
        }
        tie(ip, num_count, dots_count, ip_is_valid) = check_number_is_valid(s, ip, i, num_count, dots_count, ip_is_valid);
        if (!ip_is_valid) {
            break;
        }
    }
    if (dots_count != 3) {
        ip_is_valid = false;
    }
    if (!ip_is_valid) {
        valid_ip = "NO";
    }
    cout << valid_ip;
    return 0;
}