Return
Two integers m and a are given. If there is no reverse number to A module M, output number -1, and if it exists, output this number (the answer must lie within 0 to M-1).

Input
Two integers are given in the only line of input data 1

output
Display the answer to the task.

Examples
Input
179 57.
Output
22

b = 0
A = List (MAP (int, input (). Split ()))
B = POW (A [1], A [0] - 2, A [0])
IF POW (A [1], A [0] - 2, A [0]) == 0:
  Print (-1)
ELSE:
  Print (B)

Answer 1, Authority 100%

Solution using an extended Euclidea algorithm. The method through the degree requires calculating the Euler function. E-MAXX

def gcdextended (a, b):
  IF a == 0:
    Return B, 0.1
  GCD, X1, Y1 = GCDextended (B% A, A)
  x = y1 - (b // a) * x1
  y = x1.
  Return GCD, X, Y
M, A = MAP (int, input (). Split ())
GCD, X, Y = GCDextended (A, M)
IF GCD == 1:
  Print ((x% m + m)% m)
ELSE:
  Print (-1)