calculate modular inverse python

# Iterative Python 3 program to find 
# modular inverse using extended 
# Euclid algorithm 
  
# Returns modulo inverse of a with 
# respect to m using extended Euclid 
# Algorithm Assumption: a and m are 
# coprimes, i.e., gcd(a, m) = 1 
def modInverse(a, m) : 
    m0 = m 
    y = 0
    x = 1
  
    if (m == 1) : 
        return 0
  
    while (a > 1) : 
  
        # q is quotient 
        q = a // m 
  
        t = m 
  
        # m is remainder now, process 
        # same as Euclid's algo 
        m = a % m 
        a = t 
        t = y 
  
        # Update x and y 
        y = x - q * y 
        x = t 
  
  
    # Make x positive 
    if (x < 0) : 
        x = x + m0 
  
    return x 
  
  
# Driver program to test above function 
a = 3
m = 11
print("Modular multiplicative inverse is", 
       modInverse(a, m)) 
  
# This code is contributed by Nikita tiwari.