from math import factorial

# Comninatorics:  n choose m
def nCm(n,m):
    y = int( ( factorial(n) / factorial(m) ) / factorial(n-m) )
    return(y)

# permitations: N pick M
def nPm(n,m):
    y = int( factorial(n) / factorial(n-m) )
    return(y)