grassshop.cpp

#include <stdlib.h>
#include <stdio.h>
 
int pole[100][100];
int posSx, posSy;
int posFx, posFy;
int sizex, sizey;
 
void check(int x, int y, int jump)
{
	if(x > -1 && y > -1 && x < sizex && y < sizey)
	{
		if(pole[x][y]>jump)
{		
			pole[x][y] = jump;
			check(x+2, y+1,jump+1);
			check(x+2, y-1,jump+1);
			check(x-2, y+1,jump+1);
			check(x-2, y-1,jump+1);
			check(x+1, y+2,jump+1);
			check(x+1, y-2,jump+1);
			check(x-1, y+2,jump+1);
			check(x-1, y-2,jump+1);
		}
	}
 
}
 
 
int main(void)
{
 
	while(scanf("%d %d %d %d %d %d", &sizex, &sizey, &posSx, &posSy, &posFx, &posFy) == 6)
	{
		for(int i = 0; i<sizex; i++)
			for(int j = 0; j<sizey; j++)
				pole[i][j] = 1000;
 
		check(posSx-1, posSy-1, 0);
 
 
		if(pole[posFx-1][posFy-1]==1000)
			printf("impossible\n");
		else
			printf("%d\n", pole[posFx-1][posFy-1]);
	}
 
	return 0;
 
}