n, k = map(int, input().split())
d = [-1] * n
for _ in range(k):
    a, c = input().split()
    d[int(a) - 1] = 'RGB'.find(c)
ans = [0] * n
now = 0
for i in range(n):
    if i % 3 == 0:
        now = 7
    if d[i] == -1 or not now >> d[i] & 1:
        k = 0
        while not now >> k & 1:
            k += 1
    else:
        k = d[i]
    ans[i] = k
    now &= ~(1 << k)
print(''.join('RGB'[c] for c in ans))