#include <iostream>
#include <cmath>

using namespace std;
// function prototype
int convert(long long);
// function definition
int convert(long long n) {
  int dec = 0, i = 0, rem;
  while (n!=0) {
    rem = n % 10;
    n /= 10;
    dec += rem * pow(2, i);
    ++i;
  }
  return dec;
}