|Codeforces Round #167 (Div. 1)|
Dima loves making pictures on a piece of squared paper. And yet more than that Dima loves the pictures that depict one of his favorite figures.
A piece of squared paper of size n × m is represented by a table, consisting of n rows and m columns. All squares are white on blank squared paper. Dima defines a picture as an image on a blank piece of paper, obtained by painting some squares black.
The picture portrays one of Dima's favorite figures, if the following conditions hold:
Now Dima is wondering: how many paintings are on an n × m piece of paper, that depict one of his favorite figures? Count this number modulo 1000000007 (109 + 7).
The first line contains two integers n and m — the sizes of the piece of paper (1 ≤ n, m ≤ 150).
In a single line print the remainder after dividing the answer to the problem by number 1000000007 (109 + 7).