#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<ctype.h>
char s[100];
int main(){
    scanf("%s",&s);
    int len = strlen(s),i,j;
    long long a = 0,t = 0;
    for(i=0;i<len;i++){
        t = s[i] - '0'; 
        for(j=1;j<=len-i-1;j++){
            t = t * 2;
        }
        a = a + t;
    }
    printf("%lld",a);
    return 0;
}
/**************************************************************
	Problem: 1290
	User: admin
	Language: C
	Result: Accepted
	Time:18 ms
	Memory:1144 kb
****************************************************************/