Decimal to Binary Converter - A

#include <iostream>

using namespace std;

#define s(x) (int)x.size()

int main() {
  int mask;
  scanf("%d", &mask);

  string bin = "";

  for (int i = 0; i < 31; ++i) {
    if(mask & (1 << i)) bin += '1';
    else bin += '0';
  }

  while(s(bin) > 1 && bin.back() == '0') bin.pop_back();

  for (int i = s(bin) - 1; i >= 0; --i) cout<<bin[i];
  cout<<'\n';
}