b2.cpp

#include <bits/stdc++.h>
using namespace std;

int main() {
  string s, s1;
  cout << "Nhap xau s: ";
  getline(cin, s);
  for (int i = 0; i < s.size(); i++) {
    if (isdigit(s[i]) && s[i] != '0') s1 += s[i];
  }
  cout << "Xau s1 la: " << s1 << endl;
}