/*	Reads an integer from stdin and prints it
	on stdout in octal base; */ 

#include <stdio.h>
#include <stdlib.h>

#define MAX_LEN 100
#define ERR_MSG_NEG "Err: the number is negative"

int main (void)
{
	int num;
	char buffer[MAX_LEN];

	if(!fgets(buffer, MAX_LEN, stdin)) return 1;

/*	Converts the input str to int, if the number
	is negative, puts an error message on stderr;	*/
	if((num = atoi(buffer)) < 0 ) {
		fprintf(stderr, "%s\n", ERR_MSG_NEG);
		return 1;
	}
	
/*	prints the integer in octal base;	*/
	printf("%o\n", num);
	return 0;
}