n,k=map(int,input().split())
x=[""]*n
for i in range(k):
    a,b=input().split()
    x[int(a)-1]=b
ans=[]
for i in range(0,n,3):
    s=set()
    d=[""]*3
    for j in range(3):
    	if i+j>=n:
    	    break
    	if x[i+j] not in s:
            d[j]=x[i+j]
            s.add(x[i+j])
    for j in ["R","G","B"]:
        if j not in s:
            for l in range(3):
            	if d[l]=="":
            		d[l]=j
            		break
    ans+=d
print("".join(ans[:n]))