Decimal to Binary Converter - B

#include <iostream>

using namespace std;

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

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

  string bin = (mask ? "" : "0");

  while(mask)
    bin += (mask & 1 ? '1' : '0'), mask >>= 1;

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