# とにかくできるだけイーブンにR, G, Bを増やしていく
# 証言は順番昇順でソート
# 証言の色が足らなければ増やす、そうでなければイーブンにする
# 同順位でいいので不可能はないはず

N, K = map(int, input().split())
testimony = {}
for i in range(K):
    a, c = map(str, input().split())
    if c == 'R':
        testimony[int(a)] = 0
    elif c == 'G':
        testimony[int(a)] = 1
    elif c == 'B':
        testimony[int(a)] = 2

RGB = [0, 0, 0]
ans = ''
string = 'RGB'

for i in range(N):
    smallest_num = min(RGB)
    if i+1 in testimony:
        if RGB[testimony[i+1]] == smallest_num:
            RGB[testimony[i+1]] += 1
            ans += string[testimony[i+1]]
        else:
            for j in range(3):
                if RGB[j] == smallest_num:
                    RGB[j] += 1
                    ans += string[j]
                    break
    else:
        for j in range(3):
            if RGB[j] == smallest_num:
                RGB[j] += 1
                ans += string[j]
                break
    #print('i', i, 'RGB', RGB, 'ans', ans)
print(ans)