"""

"""

import sys
from sys import stdin

N,K = map(int,stdin.readline().split())

clis = [None] * N

for i in range(K):
    a,c = input().split()
    clis[int(a)-1] = c

R,G,B = 0,0,0
ans = []

for i in range(N):

    nmin = min(R,G,B)
    if clis[i] == None:
        if nmin == R:
            now = "R"
        elif nmin == G:
            now = "G"
        else:
            now = "B"
            
    elif clis[i] == "R":
        if nmin == R:
            now = "R"
        elif nmin == G:
            now = "G"
        else:
            now = "B"

    elif clis[i] == "G":

        if nmin == G:
            now = "G"
        elif nmin == R:
            now = "R"
        else:
            now = "B"

    elif clis[i] == "B":

        if nmin == B:
            now = "B"
        elif nmin == R:
            now = "R"
        else:
            now = "G"

    if now == "R":
        R += 1
    elif now == "G":
        G += 1
    else:
        B += 1

    ans.append(now)

print (*ans,sep="")