N, K = map(int, input().split())
c = {j:i for i,j in enumerate('RGB')}
rc = {i:j for i,j in enumerate('RGB')}

p = []
for i in range(K):
    a, b = map(str, input().split())
    p.append([int(a),b])
p.sort()

res = []
num = [0,0,0]
for i in range(K):
    a, b = p[i]
    n1, n2 = a//3,a%3
    res.append('R'*(n1-num[0])+'G'*(n1-num[1])+'B'*(n1-num[2]))
    num[0] += n1-num[0]
    num[1] += n1-num[1]
    num[2] += n1-num[2]
    if n2==1:
        num[c[b]] += 1
        res.append(b)
    if n2==2:
        num[c[b]] += 1
        num[(c[b]+1)%3] += 1
        res.append(b)
        res.append(rc[(c[b]+1)%3])

ans = ''.join(res)
if len(ans)!=N:
    ans += 'R'*(N-len(ans))

debug = [[0]*3 for _ in range(N)]
for i in range(N):
    debug[i][c[ans[i]]] += 1
    if i>0:
        for j in range(3):
            debug[i][j] += debug[i-1][j]

for a, b in p:
    assert debug[a-1][c[b]] == max(debug[a-1])

print(ans)