#include <stdio.h>
#include <stdint.h>
uint16_t binary_to_uint(const char *str) {
// Your logic here
int len = 0 ;
const char *tmp = str;
uint16_t res = 0;
while(*tmp)
{
len++;
tmp++;
}
for(int n = 0 ; n < len ; n++)
{
if(str[len - n - 1] == '1')
{
res |= 1<<n;
}
}
return res;
}
int main() {
char bin[20];
scanf("%s", bin);
printf("%u", binary_to_uint(bin));
return 0;
}