#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;
}