#include <stdio.h>
#define MAX 1000
int main()
{
int htoi(char s[]);

int c,i=0;
char t[MAX];

while((c=getchar())!='\n'&&i<MAX)
     if(c>='0'&&c<='9'||c>='a'&&c<='f'||c>='A'&&c<='F') t[i++]=c;             

t[i]='\0';
printf("%d",htoi(t));
return 0;
}


int htoi(char s[])
{
int i,n;
n=0;
for(i=0;s[i]!='\0';i++)
	{
	if(s[i]>='0'&&s[i]<='9')
    	n=n*16+s[i]-'0';
	if(s[i]>='a'&&s[i]<='f')
	    n=n*16+s[i]-'a'+10;
	if(s[i]>='A'&&s[i]<='F')
    	n=n*16+s[i]-'A'+10;
	}
return (n);
}