N, K = map(int, input().split())
A = [-1]*N
S = 'RGB'
for _ in range(K):
    a, b = input().split()
    A[int(a)-1] = S.index(b)

ans = [-1]*N
ct = [0]*3
for i in range(N):
    if A[i] >= 0 and ct[A[i]] == min(ct):
        ans[i] = A[i]
    else:
        ans[i] = ct.index(min(ct))
    ct[ans[i]] += 1

print(''.join(S[a] for a in ans))