def number1():
x1=float(input('x1 '))
y1=float(input('y1 '))
x2=float(input('x2 '))
y2=float(input('y2 '))
if x1==x2:
return 'y=inf'
else:
k=(y1-y2)/(x1-x2)
b=y1-k*x1
if b==0:
return 'y=%.1fx' %(k)
else:
return 'y=%.1fx+%.1f' % (k,b) , number1()
print (number1())