# Python program to calculate the sum of the positive integers of n+(n-2)+(n-4)... (until n-x =< 0)

def sum_series(n):  
  if n < 1:  
    return 0  
  else:  
    return n + sum_series(n - 2)  
  
print(sum_series(6))  
print(sum_series(10))