Buggy python submission (verdict: Time Limit Exceeded):
import sys
sys.setrecursionlimit(10**8)
def ii(): return int(sys.stdin.readline())
def mi(): return map(int, sys.stdin.readline().split())
def li(): return list(map(int, sys.stdin.readline().split()))
def li2(N): return [list(map(int, sys.stdin.readline().split())) for i in range(N)]
def dp2(ini, i, j): return [[ini]*i for i2 in range(j)]
def dp3(ini, i, j, k): return [[[ini]*i for i2 in range(j)] for i3 in range(k)]
import copy
#import bisect #bisect.bisect_left(B, a)
#from collections import defaultdict #d = defaultdict(int) d[key] += value
#from collections import Counter # a = Counter(A).most_common()
#from itertools import accumulate #list(accumulate(A))
 
N, *D = mi()
S = [sys.stdin.readline()[:2] for _ in range(N)]
ans = [0]*N
 
def cv(m):
    if m == 'A':
        return 0
    if m == 'B':
        return 1
    if m == 'C':
        return 2
 
def dfs(i, D, ans):
    if D[0]<0 or D[1]<0 or D[2]<0:
        return
    if i == N:
        print('Yes')
        for m in ans:
            print(m)
        exit()
    s, t = cv(S[i][0]), cv(S[i][1])
    D_ = copy.deepcopy(D)
    ans_ = copy.deepcopy(ans)
    D[s] += 1
    D[t] -= 1
    ans[i] = S[i][0]
    dfs(i+1, D, ans)
    D_[s] -= 1
    D_[t] += 1
    ans_[i] = S[i][1]
    dfs(i+1, D_, ans_)
 
dfs(0, D, ans)
print('No')

Fixed submission:
import sys
sys.setrecursionlimit(10**8)
def ii(): return int(sys.stdin.readline())
def mi(): return map(int, sys.stdin.readline().split())
def li(): return list(map(int, sys.stdin.readline().split()))
def li2(N): return [list(map(int, sys.stdin.readline().split())) for i in range(N)]
def dp2(ini, i, j): return [[ini]*i for i2 in range(j)]
def dp3(ini, i, j, k): return [[[ini]*i for i2 in range(j)] for i3 in range(k)]
#import bisect #bisect.bisect_left(B, a)
#from collections import defaultdict #d = defaultdict(int) d[key] += value
#from collections import Counter # a = Counter(A).most_common()
#from itertools import accumulate #list(accumulate(A))

N, *D = mi()
S = [sys.stdin.readline()[:2] for _ in range(N)]
ans = [0]*N

def cv(m):
    if m == 'A':
        return 0
    if m == 'B':
        return 1
    if m == 'C':
        return 2

def dfs(i, A, B, C, ans):
    if A<0 or B<0 or C<0:
        return
    if i == N:
        print('Yes')
        for m in ans:
            print(m)
        exit()
    #s, t = cv(S[i][0]), cv(S[i][1])
    '''
    D[s] += 1
    D[t] -= 1
    ans[i] = S[i][0]
    dfs(i+1, D, ans)
    D_[s] -= 1
    D_[t] += 1
    ans_[i] = S[i][1]
    dfs(i+1, D_, ans_)
    '''
    if S[i] == 'AB':
        ans[i] = 'A'
        dfs(i+1, A+1, B-1, C, ans)
        ans[i] = 'B'
        dfs(i+1, A-1, B+1, C, ans)
    if S[i] == 'BC':
        ans[i] = 'B'
        dfs(i+1, A, B+1, C-1, ans)
        ans[i] = 'C'
        dfs(i+1, A, B-1, C+1, ans)
    if S[i] == 'AC':
        ans[i] = 'A'
        dfs(i+1, A+1, B, C-1, ans)
        ans[i] = 'C'
        dfs(i+1, A-1, B, C+1, ans)

dfs(0, D[0], D[1], D[2], ans)
print('No')

Buggy python submission (verdict: Time Limit Exceeded):
import sys
sys.setrecursionlimit(10**8)
def ii(): return int(sys.stdin.readline())
def mi(): return map(int, sys.stdin.readline().split())
def li(): return list(map(int, sys.stdin.readline().split()))
def li2(N): return [list(map(int, sys.stdin.readline().split())) for i in range(N)]
def dp2(ini, i, j): return [[ini]*i for i2 in range(j)]
def dp3(ini, i, j, k): return [[[ini]*i for i2 in range(j)] for i3 in range(k)]
import copy
#import bisect #bisect.bisect_left(B, a)
#from collections import defaultdict #d = defaultdict(int) d[key] += value
#from collections import Counter # a = Counter(A).most_common()
#from itertools import accumulate #list(accumulate(A))
 
N, *D = mi()
S = [sys.stdin.readline()[:2] for _ in range(N)]
ans = [0]*N
 
def cv(m):
    if m == 'A':
        return 0
    if m == 'B':
        return 1
    if m == 'C':
        return 2
 
def dfs(i, D, ans):
    if D[0]<0 or D[1]<0 or D[2]<0:
        return
    if i == N:
        print('Yes')
        for m in ans:
            print(m)
        exit()
    s, t = cv(S[i][0]), cv(S[i][1])
    D_ = copy.deepcopy(D)
    ans_ = copy.deepcopy(ans)
    D[s] += 1
    D[t] -= 1
    ans[i] = S[i][0]
    dfs(i+1, D, ans)
    D_[s] -= 1
    D_[t] += 1
    ans_[i] = S[i][1]
    dfs(i+1, D_, ans_)
 
dfs(0, D, ans)
print('No')

Fixed submission:
import sys
sys.setrecursionlimit(10**8)
def ii(): return int(sys.stdin.readline())
def mi(): return map(int, sys.stdin.readline().split())
def li(): return list(map(int, sys.stdin.readline().split()))
def li2(N): return [list(map(int, sys.stdin.readline().split())) for i in range(N)]
def dp2(ini, i, j): return [[ini]*i for i2 in range(j)]
def dp3(ini, i, j, k): return [[[ini]*i for i2 in range(j)] for i3 in range(k)]
#import bisect #bisect.bisect_left(B, a)
#from collections import defaultdict #d = defaultdict(int) d[key] += value
#from collections import Counter # a = Counter(A).most_common()
#from itertools import accumulate #list(accumulate(A))

N, *D = mi()
S = [sys.stdin.readline()[:2] for _ in range(N)]
ans = [0]*N

def cv(m):
    if m == 'A':
        return 0
    if m == 'B':
        return 1
    if m == 'C':
        return 2

def dfs(i, A, B, C, ans):
    if A<0 or B<0 or C<0:
        return
    if i == N:
        print('Yes')
        for m in ans:
            print(m)
        exit()
    #s, t = cv(S[i][0]), cv(S[i][1])
    '''
    D[s] += 1
    D[t] -= 1
    ans[i] = S[i][0]
    dfs(i+1, D, ans)
    D_[s] -= 1
    D_[t] += 1
    ans_[i] = S[i][1]
    dfs(i+1, D_, ans_)
    '''
    if S[i] == 'AB':
        ans[i] = 'A'
        dfs(i+1, A+1, B-1, C, ans)
        ans[i] = 'B'
        dfs(i+1, A-1, B+1, C, ans)
    if S[i] == 'BC':
        ans[i] = 'B'
        dfs(i+1, A, B+1, C-1, ans)
        ans[i] = 'C'
        dfs(i+1, A, B-1, C+1, ans)
    if S[i] == 'AC':
        ans[i] = 'A'
        dfs(i+1, A+1, B, C-1, ans)
        ans[i] = 'C'
        dfs(i+1, A-1, B, C+1, ans)

dfs(0, D[0], D[1], D[2], ans)
print('No')