#include<stdio.h>
#include<math.h>
void main()
{
	int m,n,x,y,t,L;
	scanf("%ld %ld %ld %ld %ld",&m,&n,&x,&y,&L);
	if(x!=y&&x<2000000000&&y<20000000000&&m<2000000000&&n<2000000000&&L<2100000000&&(abs(x-y)+L)%abs(m-n)==0)
	{t=( abs(x-y)+L)/abs(m-n);
	printf("%ld\n",t);}
	else printf("impossible\n");
}