AT_abc454_c [ABC454C] Straw Millionaire

There are $ N $ types of items item $ 1 $ through item $ N $ . Initially, Takahashi has only item $ 1 $ . He has $ M $ friends. If he gives item $ A_i $ to the $ i $ -th friend $ (1\le i\le M) $ , he will receive item $ B_i $ . Find how many types of items he can obtain, including item $ 1 $ .

The input is given from Standard Input in the following format: > $ N $ $ M $ $ A_1 $ $ B_1 $ $ A_2 $ $ B_2 $ $ \vdots $ $ A_M $ $ B_M $

Output the answer.

### Sample Explanation 1 For example, Takahashi can obtain item $ 4 $ by acting as follows: - Give item $ 1 $ to the first friend. Receive item $ 2 $ . - Give item $ 2 $ to the fourth friend. Receive item $ 4 $ . He can obtain four types of items: items $ 1,2,3,4 $ . Thus, output $ 4 $ . ### Sample Explanation 2 He can obtain one type of item: item $ 1 $ . ### Constraints - $ 2\le N\le 3\times 10^5 $ - $ 1\le M\le 3\times 10^5 $ - $ 1\le A_i,B_i\le N $ - $ A_i \neq B_i $ - All input values are integers.