Problem Statement

$N$ students stand in a line, each wearing a cap that is red, green, or blue. The students are numbered $1,2,\ldots,N$ from the front of the line.

You have obtained $K$ testimonies. The $i$-th testimony is as follows:

• Among the caps of the $1$-st through $A_i$-th students, one of the most frequently appearing colors is $c_i$.

Here, $c_i$ is one of R, G, B, representing red, green, and blue, respectively. Also, $A_i\ne A_j$ holds if $i\ne j$.

Based on these testimonies, find $1$ possible way the students could be wearing their caps. However, if the testimonies are contradictory, report that.

Constraints

• $1\le K\le N\le 10^5$
• $1\le A_i\le N$
• $A_i\ne A_j$ if $i\ne j$
• $c_i$ is one of R, G, B
• $N,K,A_i$ are integers

Input

$N$ $K$
$A_1$ $c_1$
$\vdots$
$A_K$ $c_K$

Output

If the testimonies are contradictory, output $-1$.

Otherwise, output $N$ characters on $1$ line. The $i$-th character should be R if the $i$-th student is wearing a red cap, G if wearing a green cap, and B if wearing a blue cap.

If there are multiple answers, you may output any of them.

Sample

5 3
3 G
5 B
1 R

RGGBB

12 5
2 R
3 R
5 R
7 R
11 B

RRRBRBRBBBBB