Buggy python submission (verdict: Runtime Error):
import sys

read = sys.stdin.buffer.read
readline = sys.stdin.buffer.readline
readlines = sys.stdin.buffer.readlines

Q, A, B, C = map(int, readline().split())
N = A + B + C
S = read().split()

S = tuple(0 if s == b'BC' else 1 if s == b'AC' else 2 for s in S)

assert N != 2

def solve_1(N, A, B, C, S):
    nums = [A, B, C]
    for s in S:
        if nums[s] == N:
            raise Exception
        i, j = (0, 1) if s == 2 else (0, 2) if s == 1 else (1, 2)
        if nums[i] < nums[j]:
            i, j = j, i
        yield j
        nums[j] += 1
        nums[i] -= 1


def solve_2(N, A, B, C, S):
    nums = [A, B, C]
    s = S[0]
    # 初手で死亡
    if nums[s] == N:
        raise Exception
    # あとはできる。きわどいときは 2 手読み
    S = S + (0, )
    for s, t in zip(S, S[1:]):
        i, j = (0, 1) if s == 2 else (0, 2) if s == 1 else (1, 2)
        if (nums[i], nums[j]) != (1, 1):
            if nums[i] < nums[j]:
                i, j = j, i
        if s != t:
            i, j = t, 3 - s - t
        yield j
        nums[j] += 1
        nums[i] -= 1

def large(N, A, B, C, S):
    nums = [A, B, C]
    for s in S:
        if nums[s] == N:
            raise Exception
        i, j = (0, 1) if s == 2 else (0, 2) if s == 1 else (1, 2)
        if nums[i] < nums[j]:
            i, j = j, i
        yield j
        nums[j] += 1
        nums[i] -= 1

f = solve_1 if N == 1 else solve_2 if N == 2 else large

try:
    cmds = list(f(N,A,B,C,S))
    print('Yes')
    answer = ('ABC'[i] for i in cmds)
    print('\n'.join(answer))
except Exception:
    print('No')
    exit()


Fixed submission:
import sys

read = sys.stdin.buffer.read
readline = sys.stdin.buffer.readline
readlines = sys.stdin.buffer.readlines

Q, A, B, C = map(int, readline().split())
N = A + B + C
S = read().split()

S = tuple(0 if s == b'BC' else 1 if s == b'AC' else 2 for s in S)

def solve_1(N, A, B, C, S):
    nums = [A, B, C]
    for s in S:
        if nums[s] == N:
            raise Exception
        i, j = (0, 1) if s == 2 else (0, 2) if s == 1 else (1, 2)
        if nums[i] < nums[j]:
            i, j = j, i
        yield j
        nums[j] += 1
        nums[i] -= 1

def solve_2(N, A, B, C, S):
    nums = [A, B, C]
    s = S[0]
    # 初手で死亡
    if nums[s] == N:
        raise Exception
    # あとはできる。きわどいときは 2 手読み
    S = S + (0, )
    for s, t in zip(S, S[1:]):
        i, j = (0, 1) if s == 2 else (0, 2) if s == 1 else (1, 2)
        if (nums[i], nums[j]) != (1, 1):
            if nums[i] < nums[j]:
                i, j = j, i
        elif s != t:
            i, j = t, 3 - s - t
        yield j
        nums[j] += 1
        nums[i] -= 1

def large(N, A, B, C, S):
    nums = [A, B, C]
    for s in S:
        if nums[s] == N:
            raise Exception
        i, j = (0, 1) if s == 2 else (0, 2) if s == 1 else (1, 2)
        if nums[i] < nums[j]:
            i, j = j, i
        yield j
        nums[j] += 1
        nums[i] -= 1

f = solve_1 if N == 1 else solve_2 if N == 2 else large

try:
    cmds = list(f(N, A, B, C, S))
    print('Yes')
    answer = ('ABC' [i] for i in cmds)
    print('\n'.join(answer))
except Exception:
    print('No')

Buggy python submission (verdict: Runtime Error):
import sys

read = sys.stdin.buffer.read
readline = sys.stdin.buffer.readline
readlines = sys.stdin.buffer.readlines

Q, A, B, C = map(int, readline().split())
N = A + B + C
S = read().split()

S = tuple(0 if s == b'BC' else 1 if s == b'AC' else 2 for s in S)

assert N >= 3

def solve_1(N, A, B, C, S):
    nums = [A, B, C]
    for s in S:
        if nums[s] == N:
            raise Exception
        i, j = (0, 1) if s == 2 else (0, 2) if s == 1 else (1, 2)
        if nums[i] < nums[j]:
            i, j = j, i
        yield j
        nums[j] += 1
        nums[i] -= 1


def solve_2(N, A, B, C, S):
    nums = [A, B, C]
    s = S[0]
    # 初手で死亡
    if nums[s] == N:
        raise Exception
    # あとはできる。きわどいときは 2 手読み
    S = S + (0, )
    for s, t in zip(S, S[1:]):
        i, j = (0, 1) if s == 2 else (0, 2) if s == 1 else (1, 2)
        if (nums[i], nums[j]) != (1, 1):
            if nums[i] < nums[j]:
                i, j = j, i
        if s != t:
            i, j = t, 3 - s - t
        yield j
        nums[j] += 1
        nums[i] -= 1

def large(N, A, B, C, S):
    nums = [A, B, C]
    for s in S:
        if nums[s] == N:
            raise Exception
        i, j = (0, 1) if s == 2 else (0, 2) if s == 1 else (1, 2)
        if nums[i] < nums[j]:
            i, j = j, i
        yield j
        nums[j] += 1
        nums[i] -= 1

f = solve_1 if N == 1 else solve_2 if N == 2 else large

try:
    cmds = list(f(N,A,B,C,S))
    print('Yes')
    answer = ('ABC'[i] for i in cmds)
    print('\n'.join(answer))
except Exception:
    print('No')
    exit()


Fixed submission:
import sys

read = sys.stdin.buffer.read
readline = sys.stdin.buffer.readline
readlines = sys.stdin.buffer.readlines

Q, A, B, C = map(int, readline().split())
N = A + B + C
S = read().split()

S = tuple(0 if s == b'BC' else 1 if s == b'AC' else 2 for s in S)

def solve_1(N, A, B, C, S):
    nums = [A, B, C]
    for s in S:
        if nums[s] == N:
            raise Exception
        i, j = (0, 1) if s == 2 else (0, 2) if s == 1 else (1, 2)
        if nums[i] < nums[j]:
            i, j = j, i
        yield j
        nums[j] += 1
        nums[i] -= 1

def solve_2(N, A, B, C, S):
    nums = [A, B, C]
    s = S[0]
    # 初手で死亡
    if nums[s] == N:
        raise Exception
    # あとはできる。きわどいときは 2 手読み
    S = S + (0, )
    for s, t in zip(S, S[1:]):
        i, j = (0, 1) if s == 2 else (0, 2) if s == 1 else (1, 2)
        if (nums[i], nums[j]) != (1, 1):
            if nums[i] < nums[j]:
                i, j = j, i
        elif s != t:
            i, j = t, 3 - s - t
        yield j
        nums[j] += 1
        nums[i] -= 1

def large(N, A, B, C, S):
    nums = [A, B, C]
    for s in S:
        if nums[s] == N:
            raise Exception
        i, j = (0, 1) if s == 2 else (0, 2) if s == 1 else (1, 2)
        if nums[i] < nums[j]:
            i, j = j, i
        yield j
        nums[j] += 1
        nums[i] -= 1

f = solve_1 if N == 1 else solve_2 if N == 2 else large

try:
    cmds = list(f(N, A, B, C, S))
    print('Yes')
    answer = ('ABC' [i] for i in cmds)
    print('\n'.join(answer))
except Exception:
    print('No')