#include<stdio.h>
#include<string.h>
int main(){
    char b[33];
    int i,n;
    int dec = 0;
    scanf("%s", b);
    n = strlen(b);
    for (i = 0; i < n; i++){
        if (b[i] !='0' && b[i] !='1')
        printf("Invaid Input");
        return 0;
    }
}
     for (i = n - 1, i > 0, i--) {
         if(b[i] =='1')
         dec += 1 << (n - 1 - i);
     }
     if (b[0] =='1')
     dec -= 1 << (n - 1);
        printf("%d", dec);
      return 0;
}