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

#define READ_BUFSIZE ( 16 )
#define READ_DELIMITER ( " " )


//標準入力取得（１行）

int GetStdin( char* pszStr, int lMaxLen )
{
	int lLen = 0;

    memset( pszStr, 0, lMaxLen );
    if( fgets( pszStr, lMaxLen, stdin ) )
    {
	    lLen = strlen( pszStr );
	    if( lLen >= 1 )
	    {
			if( pszStr[ lLen - 1 ] == 0x0A )
			{
				pszStr[ lLen - 1 ] = 0;
				lLen--;
			}
		}
	}
	
	return( lLen );
}



int main(int argc, char *argv[]) 
{
	char szRead[READ_BUFSIZE] = "";
	//char* psOutbuf[10000] = { 0 };
	//int lInput[10] = {0};

	GetStdin( szRead, READ_BUFSIZE );
	int X = atoi( szRead );

	GetStdin( szRead, READ_BUFSIZE );
	int Y = atoi( szRead );

	GetStdin( szRead, READ_BUFSIZE );
	int L = atoi( szRead );


	int lCount = 0;
	if( Y >= 0 )
	{
		if( X != 0 )
			lCount = 1;
	}
	else
		lCount = 2;


	lCount += abs( X / L );
	if( X % L )
		lCount++;

	lCount += abs( Y / L );
	if( Y % L )
		lCount++;


	printf( "%d", lCount );

	return 0;

}