Description

Given an $n \times m$ matrix, ask how many paths there are from the top-left corner to the bottom-right corner. Retain 17 significant digits (that is, starting from the 18th significant digit, output 0).

Input Format

A single line with two positive integers $n, m$.

Output Format

The number of paths $t$.

6 4

210

Hint

Constraints: $1 \le n \le 10^8, 1 \le m \le 4$.

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