Buggy python submission (verdict: Runtime Error):
#!/usr/bin/env python
# -*- coding: utf-8 -*-

import sys
sys.setrecursionlimit(10**7)
from pprint import pprint as pp
from pprint import pformat as pf

import math
#from sortedcontainers import SortedList, SortedDict, SortedSet # no in atcoder
import bisect


class Player():

    A = 0
    B = 1
    C = 2

    def __init__(self, data, op_list):
        self.data = data
        self.op_list = op_list
        self.move_history = ["X"] * len(self.op_list)
        self.key = 0
        self.ans = "Yes" # "Yes" or "No"
        self.flg_out = False
        self.flg_foresight = False
        s = sum(data)
        if s == 2:
            self.flg_foresight = True
        elif s == 0 or s == 1:
            self.ans = "No"
            self.flg_out = True

    def has_next_op(self):
        if self.key < len(self.op_list):
            return True
        else:
            return False

    def play(self):
        for key, op in enumerate(op_list):
            if self.flg_out:
                break
            self.key = key
            self.read_op(op)

    def read_op(self, op):
        if op == "AB":
            self.do(self.A, self.B)
        if op == "AC":
            self.do(self.A, self.C)
        if op == "BC":
            self.do(self.B, self.C)

    def do(self, x, y):
        if self.data[x] < self.data[y]:
            self.move(y, x)
        elif self.data[x] > self.data[y]:
            self.move(x, y)
        else: # same
            if self.flg_foresight:
                if self.is_next_used(x):
                    self.move(y, x)
                else:
                    self.move(x, y)
            else:
                self.move(x, y) # which is ok

    def move(self, frm, to):
        self.move_history[self.key] = self.num_to_char(to)
        self.data[frm] -= 1
        self.data[to] += 1
        if self.data[frm] < 0:
            self.ans = "No"
            self.flg_out = True

    @staticmethod
    def num_to_char(z):
        chars = ['A', 'B', 'C']
        return chars[z]

    def is_next_used(self, z):
        if not self.has_next_op():
            return True # which is ok
        next_op = self.op_list[self.key + 1]
        if self.num_to_char(z) in next_op:
            return True
        else:
            return False

    def print_ans(self):
        print(self.ans)
        if self.ans == "No":
            return
        for h in self.move_history:
            print(h)




if __name__ == '__main__':
    n, a, b, c = list(map(int, input().split()))
    data = [a, b, c]
    #print('data') # debug
    #print(data) # debug
    op_list = [""] * n
    for i in range(n):
        op_list[i] = input()
    #print('op_list') # debug
    #print(op_list) # debug

    p = Player(data, op_list)
    p.play()
    p.print_ans()


    #print('\33[32m' + 'end' + '\033[0m') # debug


Fixed submission:
#!/usr/bin/env python
# -*- coding: utf-8 -*-

import sys
sys.setrecursionlimit(10**7)
from pprint import pprint as pp
from pprint import pformat as pf

import math
#from sortedcontainers import SortedList, SortedDict, SortedSet # no in atcoder
import bisect


class Player():

    A = 0
    B = 1
    C = 2

    def __init__(self, data, op_list):
        self.data = data
        self.op_list = op_list
        self.move_history = ["X"] * len(self.op_list)
        self.key = 0
        self.ans = "Yes" # "Yes" or "No"
        self.flg_out = False
        self.flg_foresight = False
        s = sum(data)
        if s == 2:
            self.flg_foresight = True
        elif s == 0:
            self.ans = "No"
            self.flg_out = True

    def has_next_op(self):
        if self.key + 1 < len(self.op_list):
            return True
        else:
            return False

    def play(self):
        for key, op in enumerate(op_list):
            #print('self.data') # debug
            #print(self.data) # debug
            if self.flg_out:
                break
            self.key = key
            self.read_op(op)

    def read_op(self, op):
        if op == "AB":
            self.do(self.A, self.B)
        if op == "AC":
            self.do(self.A, self.C)
        if op == "BC":
            self.do(self.B, self.C)

    def do(self, x, y):
        if self.data[x] < self.data[y]:
            self.move(y, x)
        elif self.data[x] > self.data[y]:
            self.move(x, y)
        else: # same
            if self.flg_foresight:
                if self.is_next_used(x):
                    self.move(y, x)
                else:
                    self.move(x, y)
            else:
                self.move(x, y) # which is ok

    def move(self, frm, to):
        self.move_history[self.key] = self.num_to_char(to)
        self.data[frm] -= 1
        self.data[to] += 1
        if self.data[frm] < 0:
            self.ans = "No"
            self.flg_out = True

    @staticmethod
    def num_to_char(z):
        chars = ['A', 'B', 'C']
        return chars[z]

    def is_next_used(self, z):
        if not self.has_next_op():
            return False
        next_op = self.op_list[self.key + 1]
        if self.num_to_char(z) in next_op:
            return True
        else:
            return False

    def print_ans(self):
        print(self.ans)
        if self.ans == "No":
            return
        for h in self.move_history:
            print(h)




if __name__ == '__main__':
    n, a, b, c = list(map(int, input().split()))
    data = [a, b, c]
    #print('data') # debug
    #print(data) # debug
    op_list = [""] * n
    for i in range(n):
        op_list[i] = input()
    #print('op_list') # debug
    #print(op_list) # debug

    p = Player(data, op_list)
    p.play()
    p.print_ans()


    #print('\33[32m' + 'end' + '\033[0m') # debug

Buggy python submission (verdict: Runtime Error):
#!/usr/bin/env python
# -*- coding: utf-8 -*-

import sys
sys.setrecursionlimit(10**7)
from pprint import pprint as pp
from pprint import pformat as pf

import math
#from sortedcontainers import SortedList, SortedDict, SortedSet # no in atcoder
import bisect


class Player():

    A = 0
    B = 1
    C = 2

    def __init__(self, data, op_list):
        self.data = data
        self.op_list = op_list
        self.move_history = ["X"] * len(self.op_list)
        self.key = 0
        self.ans = "Yes" # "Yes" or "No"
        self.flg_out = False
        self.flg_foresight = False
        s = sum(data)
        if s == 2:
            self.flg_foresight = True
        elif s == 0 or s == 1:
            self.ans = "No"
            self.flg_out = True

    def has_next_op(self):
        if self.key < len(self.op_list):
            return True
        else:
            return False

    def play(self):
        for key, op in enumerate(op_list):
            if self.flg_out:
                break
            self.key = key
            self.read_op(op)

    def read_op(self, op):
        if op == "AB":
            self.do(self.A, self.B)
        if op == "AC":
            self.do(self.A, self.C)
        if op == "BC":
            self.do(self.B, self.C)

    def do(self, x, y):
        if self.data[x] < self.data[y]:
            self.move(y, x)
        elif self.data[x] > self.data[y]:
            self.move(x, y)
        else: # same
            if self.flg_foresight:
                if self.is_next_used(x):
                    self.move(y, x)
                else:
                    self.move(x, y)
            else:
                self.move(x, y) # which is ok

    def move(self, frm, to):
        self.move_history[self.key] = self.num_to_char(to)
        self.data[frm] -= 1
        self.data[to] += 1
        if self.data[frm] < 0:
            self.ans = "No"
            self.flg_out = True

    @staticmethod
    def num_to_char(z):
        chars = ['A', 'B', 'C']
        return chars[z]

    def is_next_used(self, z):
        if not self.is_next_op():
            return True # which is ok
        next_op = self.op_list[self.key + 1]
        if self.num_to_char(z) in next_op:
            return True
        else:
            return False

    def print_ans(self):
        print(self.ans)
        if self.ans == "No":
            return
        for h in self.move_history:
            print(h)




if __name__ == '__main__':
    n, a, b, c = list(map(int, input().split()))
    data = [a, b, c]
    #print('data') # debug
    #print(data) # debug
    op_list = [""] * n
    for i in range(n):
        op_list[i] = input()
    #print('op_list') # debug
    #print(op_list) # debug

    p = Player(data, op_list)
    p.play()
    p.print_ans()


    #print('\33[32m' + 'end' + '\033[0m') # debug


Fixed submission:
#!/usr/bin/env python
# -*- coding: utf-8 -*-

import sys
sys.setrecursionlimit(10**7)
from pprint import pprint as pp
from pprint import pformat as pf

import math
#from sortedcontainers import SortedList, SortedDict, SortedSet # no in atcoder
import bisect


class Player():

    A = 0
    B = 1
    C = 2

    def __init__(self, data, op_list):
        self.data = data
        self.op_list = op_list
        self.move_history = ["X"] * len(self.op_list)
        self.key = 0
        self.ans = "Yes" # "Yes" or "No"
        self.flg_out = False
        self.flg_foresight = False
        s = sum(data)
        if s == 2:
            self.flg_foresight = True
        elif s == 0:
            self.ans = "No"
            self.flg_out = True

    def has_next_op(self):
        if self.key + 1 < len(self.op_list):
            return True
        else:
            return False

    def play(self):
        for key, op in enumerate(op_list):
            #print('self.data') # debug
            #print(self.data) # debug
            if self.flg_out:
                break
            self.key = key
            self.read_op(op)

    def read_op(self, op):
        if op == "AB":
            self.do(self.A, self.B)
        if op == "AC":
            self.do(self.A, self.C)
        if op == "BC":
            self.do(self.B, self.C)

    def do(self, x, y):
        if self.data[x] < self.data[y]:
            self.move(y, x)
        elif self.data[x] > self.data[y]:
            self.move(x, y)
        else: # same
            if self.flg_foresight:
                if self.is_next_used(x):
                    self.move(y, x)
                else:
                    self.move(x, y)
            else:
                self.move(x, y) # which is ok

    def move(self, frm, to):
        self.move_history[self.key] = self.num_to_char(to)
        self.data[frm] -= 1
        self.data[to] += 1
        if self.data[frm] < 0:
            self.ans = "No"
            self.flg_out = True

    @staticmethod
    def num_to_char(z):
        chars = ['A', 'B', 'C']
        return chars[z]

    def is_next_used(self, z):
        if not self.has_next_op():
            return False
        next_op = self.op_list[self.key + 1]
        if self.num_to_char(z) in next_op:
            return True
        else:
            return False

    def print_ans(self):
        print(self.ans)
        if self.ans == "No":
            return
        for h in self.move_history:
            print(h)




if __name__ == '__main__':
    n, a, b, c = list(map(int, input().split()))
    data = [a, b, c]
    #print('data') # debug
    #print(data) # debug
    op_list = [""] * n
    for i in range(n):
        op_list[i] = input()
    #print('op_list') # debug
    #print(op_list) # debug

    p = Player(data, op_list)
    p.play()
    p.print_ans()


    #print('\33[32m' + 'end' + '\033[0m') # debug