```
"""
Given three numbers, find the greatest common divisor (gcd) of the three numbers
"""

# Find the greatest common divisor (GCD) of two numbers
def find_gcd(a, b): 
    while b > 0: 
        a, b = b, a % b 
  
    return a 

# Given three numbers, find the greatest common divisor (GCD) of the three numbers
def find_gcd_of_three_numbers(a, b, c): 
    gcd_a_b = find_gcd(a, b) 
    gcd_b_c = find_gcd(b, c) 
    gcd_a_c = find_gcd(a, c) 
  
    gcd = find_gcd(gcd_a_b, gcd_b_c) 
    gcd = find_gcd(gcd, gcd_a_c) 
  
    return gcd  

if __name__ == '__main__':
    print("GCD of 3 numbers is: ", end="") 
    print(find_gcd_of_three_numbers(18, 24, 30))
```
Dati tre numeri, trova il massimo comune divisore (mcd) dei tre numeri.