import sys
input = sys.stdin.readline
N,K=map(int,input().split())
AC=[input().strip().split()for _ in range(K)]

tmp = ["R" for _ in range(N)]
for a,c in AC:
    a = int(a)-1
    tmp[a] = c
ans = []
for i in range(N):
    if i%3==0:
        ans.append(tmp[i])
    elif i%3==1:
        if tmp[i] == ans[-1]:
            ans.append("G" if tmp[i]=="R" else "R")
        else:
            ans.append(tmp[i])
    else:
        s = set("RGB")
        s.discard(ans[-1])
        s.discard(ans[-2])
        ans.append(s.pop())
print("".join(ans))