View Compilation Error

0_0_34488243_26899.c: In function 'main':
0_0_34488243_26899.c:6:39: error: 'Ay2' undeclared (first use in this function)
  while(~scanf("%f%f%f%f",&x1,&y1,&x2,&Ay2))
                                       ^
0_0_34488243_26899.c:6:39: note: each undeclared identifier is reported only once for each function it appears in