Dear CF

I am trying to solve this problem from the gym, I have found that the solution to the problem is the sum of combinations:

`nc(N, K) + nc(N, K+1) + nc(N, K+2) + ... + nc(N, N)`

where `nc(i, j)`

is the number of combinations i chose j

However the input sizes of `N`

and `K`

are very large and my submission times out. Can you please advise me about a suitable approach to solve this problem?

K is quite small, so you can compute that sum by subtracting nc (N, 0) + nc (N, 1) + ... + nc (N, K — 1) from 2 ^ N (which is the sum of all binomial coefficients of order N). With a correct implementation that can work in O(K), but O(NlogMod) is definitely enough to pass as well