#include<stdio.h>
int main()
{
    long binary;
    int decimal=0;
    int base=1;
    int rem;
    
    scanf("%11d",&binary);
    while (binary>0)
    {
        rem=binary%10;
        decimal=decimal+rem*base;
        base=base*e;
        binary=binary/10;
        
    }
    printf("%d",decimal);
    return 0;
}