#include <stdio.h>
#include <stdint.h>
uint16_t hex_to_uint(const char *str) {
// Your logic here
uint16_t value = 0;
while(*str != '\0'){
value *= 16;
if(*str >= '0' && *str <= '9'){
value += *str - '0';
}
else if (*str >= 'A' && *str <= 'F'){
value += *str - 'A' + 10;
}
else if (*str >= 'a' && *str <= 'f'){
value += *str - 'a' + 10;
}
str++;
}
return value;
}
int main() {
char hex[10];
scanf("%s", hex);
printf("%u", hex_to_uint(hex));
return 0;
}