#include<stdio.h>
#include<string.h>
#include<math.h>
int main(){
    char a[34];
    scanf("%s",a);
    for(int i =0;i<strlen(a);i++){
        if(a[i]!='0'&&a[i] != '1') {
            printf("Invalid Input\n");
            return 0;
        }
    }
    int len = strlen(a);
    long long b = 0;
    if(a[0] == '1') {
        b = -(long long) pow(2, len -1 - i);
    }
    for (int i=1; i < len; i++) {
        if(a[i] == '1') {
            b +=(long long) pow(2, len -1 - i);
        }    
        }
    }
    }