def f():
	return (int(q) for q in r().split())
r=input
n=int(r())
x1,y1=f()
x2,y2=f()
s=(y2-y1)/(x2-x1)
yi=y2-(x2-1)*s
o=0
for y in range(1,n+1):
	for x in range(1,n+1):
		t=yi+(x-1)*s;o+=(t>y)^(yi<1)|(t==y)
print(o)