N, K = map(int, input().split())

a = [''] * N

for i in range(K):
    ai, ci = input().split(' ')
    a[int(ai) - 1] = ci

ans = []
r, g, b = 0, 0, 0
for i in range(N):
    if i % 3 == 0:
        r, g, b = 0, 0, 0
    if a[i] == 'R' and r == 0:
        r += 1
        ans.append('R')
    elif a[i] == 'G' and g == 0:
        g += 1
        ans.append('G')
    elif a[i] == 'B' and b == 0:
        b += 1
        ans.append('B')
    elif r == 0:
        r += 1
        ans.append('R')
    elif g == 0:
        g += 1
        ans.append('G')
    elif b == 0:
        b += 1
        ans.append('B')

print(''.join(ans))