#include <stdio.h>
#include <stdint.h>
#include <math.h>
uint16_t binary_to_uint(const char *str) {
// Your logic here
uint16_t num = 0;
uint16_t i=0;
while(*str != '\0')
{
if(*str == '1')
{
num = num <<1 | 1;
str++;
}
else
{
num = num << 1;
str++;
}
}
return num;
}
int main() {
char bin[20];
scanf("%s", bin);
printf("%u", binary_to_uint(bin));
return 0;
}