Time limit
2s
Memory limit
128 MB
Min-sik wants to decorate a Christmas tree made of N levels. The levels are numbered 1, 2, ..., N from top to bottom, and level k must contain exactly k ornaments.
Each ornament is red, green, or blue. For any level, once the colors used on that level are chosen, each chosen color must appear the same number of times. For example, placing 2 red ornaments and 1 blue ornament on level 3 is invalid because the two chosen colors have different counts. Placing 2 red ornaments and 2 blue ornaments on level 4 is valid.
Different color arrangements within the same level count as different decorations. Given the tree size and the available number of ornaments of each color, compute the number of different ways to decorate the tree.
The first line contains the tree size N, the number of red ornaments R, the number of green ornaments G, and the number of blue ornaments B.
N is at most 10. Each of R, G, and B is between 0 and 100, inclusive.
Print the number of ways to decorate the tree. If the tree cannot be decorated with the given ornaments, print 0.
The answer is at most 2^63 - 1.