CF1662M.Bottle Arrangements

Each test contains multiple test cases. The first line contains an integer $t$ ( $1\le t\le 100$ ) — the number of test cases. The descriptions of the $t$ test cases follow.

The first line of each test case contains two integers $n$ and $m$ ( $1 \le n \le 100$ , $1 \le m \le 100$ ) — the number of bottles of wine and the number of critics.

Each of the next $m$ lines contains two integers $r_i$ and $w_i$ ( $0 \le r_i, \, w_i \le 100$ , $r_i + w_i \ge 1$ ) — the number of red and white wines that the $i$ -th critic wants to taste.

For each test case, if at least one solution exists, print a string of length $n$ made up of the characters R and W, where the $j$ -th character ( $1 \le j \le n$ ) denotes the type of the wine in the $j$ -th bottle of the arrangement (R for red and W for white). If there are multiple solutions, print any.

If no solution exists, print the string IMPOSSIBLE.

In the first test case, there are $n = 5$ bottles of wine to be arranged and $m = 3$ critics. The arrangement RWRRW satisfies the requests of all three critics. Indeed:

• the first critic can choose the interval $[3, \, 3]$ , which contains exactly one bottle of red wine (note that $[1, \, 1]$ and $[4, \, 4]$ are other valid choices);
• the second critic can choose the interval $[1, \, 5]$ , which contains $3$ bottles of red wine and $2$ bottles of white wine;
• the third critic can choose the interval $[2, \, 5]$ , which contains $2$ bottles of red wine and $2$ bottles of white wine.

In the first test case, there are $n = 5$ bottles of wine to be arranged and $m = 3$ critics. The arrangement RWRRW satisfies the requests of all three critics. Indeed:

• the first critic can choose the interval $[3, \, 3]$ , which contains exactly one bottle of red wine (note that $[1, \, 1]$ and $[4, \, 4]$ are other valid choices);
• the second critic can choose the interval $[1, \, 5]$ , which contains $3$ bottles of red wine and $2$ bottles of white wine;
• the third critic can choose the interval $[2, \, 5]$ , which contains $2$ bottles of red wine and $2$ bottles of white wine.