def II(n,k,l,a,b,c):
  if (c<=1) or (c<=b) or (b>=a^n):
    return 0

  if n==1:
    if k==1:
      return ( log(min(a,c))^(l+1) - log(max(1,b))^(l+1) ) / (l+1)
    return - sum( factorial(l)/factorial(i)/(k-1)^(l+1-i) * ( log(min(a,c))^i/min(a,c)^(k-1) - log(max(1,b))^i/max(1,b)^(k-1) ) for i in range(l+1) )

  if k==1:
    return ( sum( binomial(l+1,j)*log(a)^(l+1-j)*II(n-1,1,j,a,b/a,c/a) for j in range(l+2) ) - log(b)^(l+1)*II(n-1,1,0,a,b/a,b) - II(n-1,1,l+1,a,b,c) + log(c)^(l+1)*II(n-1,1,0,a,c/a,c) ) / (l+1)
  return - sum( factorial(l)/factorial(i)/(k-1)^(l+1-i) * ( sum( binomial(i,j)*log(a)^(i-j)/a^(k-1)*II(n-1,k,j,a,b/a,c/a) for j in range(i+1) ) - log(b)^i/b^(k-1)*II(n-1,1,0,a,b/a,b) - II(n-1,k,i,a,b,c) + log(c)^i/c^(k-1)*II(n-1,1,0,a,c/a,c) ) for i in range(l+1) )