#include <stdio.h>
#include <string.h>
int main()
{
	char a[10];
	long long sum=0;
	int i,j;
	scanf("%s",a);
	for(i=0;i<strlen(a);i++)
	{
		if(a[i]>='A' && a[i]<='F')
		sum=sum*16+a[i]-'A'+10;
		else if(a[i]>='a' && a[i]<='f')
		sum=sum*16+a[i]-'a'+10;
		else if(a[i]>='0' && a[i]<='9')
		sum=sum*16+a[i]-'0';
	}
	
	printf("%I64d\n",sum);
	return 0;
	
}