P1655 Kid's Balls

A kid recently became very fond of balls. One day, he took $N$ distinct balls out of his pocket and wants to put them into $M$ identical boxes, with at least one ball in each box. He wonders how many ways there are. He tried to write a program, but since he slacks off and only watches swimming coaches on Bilibili, he asks you for help.

Multiple test cases. Each line contains two integers $N, M$.

For each test case, output a single line with the number of ways.

- For $20\%$ of the testdata, $N, M \leq 10$. - For $100\%$ of the testdata, $1 \leq N, M \leq 100$, and there are at most $10$ test cases per test file. Translated by ChatGPT 5