N,K=map(int,input().split())
s=[input().split() for i in range(K)]
l=["R" for i in range(N)]
for a,c in s:
	l[int(a)-1]=c
ans=[]
for i in range(N):
	if i%3==2:
		ans.append(".RGB"[".RGB".find(ans[-2])^".RGB".find(ans[-1])])
	if i%3==0:
		ans.append(l[i])
	if i%3==1:
		if ans[-1]==l[i]:
			ans.append("GBR"["RGB".find(ans[-1])])
		else:
			ans.append(l[i])
print("".join(ans))