CF900D Unusual Sequences

Count the number of distinct sequences $ a_{1},a_{2},...,a_{n} $ ( $ 1

The only line contains two positive integers $ x $ and $ y $ ( $ 1

Print the number of such sequences modulo $ 10^{9}+7 $ .

There are three suitable sequences in the first test: $ (3,3,3) $ , $ (3,6) $ , $ (6,3) $ . There are no suitable sequences in the second test.