Buggy python submission (verdict: Runtime Error):
import sys
sys.setrecursionlimit(20000)
n, m = map(int, input().split())
s = input()
out = [set() for _ in range(n)]
count = [[0, 0] for _ in range(n)]
def f(c):
    if c == 'A': return 0
    else: return 1
for _ in range(m):
    a, b = map(int, input().split())
    if a == b:
        count[a-1][f(s[a-1])] += 1
    elif b-1 not in out[a-1]:
        count[a-1][f(s[b-1])] += 1
        count[b-1][f(s[a-1])] += 1
    out[a-1].add(b-1)
    out[b-1].add(a-1)
elim = set()
def eliminate(x):
    elim.add(x)
    c = f(s[x])
    for node in out[x]:
        if node not in elim:
            count[node][c] -= 1
            if count[node][0] * count[node][1] == 0:
                eliminate(node)
for i in range(n):
    if i not in elim and count[i][0] * count[i][1] == 0:
        eliminate(i)
if len(elim) < n: print('Yes')
else: print('No')

Fixed submission:
import sys
sys.setrecursionlimit(200000)
n, m = map(int, input().split())
s = input()
out = [set() for _ in range(n)]
count = [[0, 0] for _ in range(n)]
def f(c):
    if c == 'A': return 0
    else: return 1
for _ in range(m):
    a, b = map(int, input().split())
    if a == b:
        count[a-1][f(s[a-1])] += 1
    elif b-1 not in out[a-1]:
        count[a-1][f(s[b-1])] += 1
        count[b-1][f(s[a-1])] += 1
    out[a-1].add(b-1)
    out[b-1].add(a-1)
elim = set()
def eliminate(x):
    elim.add(x)
    c = f(s[x])
    for node in out[x]:
        if node not in elim:
            count[node][c] -= 1
            if count[node][0] * count[node][1] == 0:
                eliminate(node)
for i in range(n):
    if i not in elim and count[i][0] * count[i][1] == 0:
        eliminate(i)
if len(elim) < n: print('Yes')
else: print('No')

Buggy python submission (verdict: Runtime Error):
n, m = map(int, input().split())
s = input()
out = [set() for _ in range(n)]
count = [[0, 0] for _ in range(n)]
def f(c):
    if c == 'A': return 0
    else: return 1
for _ in range(m):
    a, b = map(int, input().split())
    if a == b:
        count[a-1][f(s[a-1])] += 1
    elif b-1 not in out[a-1]:
        count[a-1][f(s[b-1])] += 1
        count[b-1][f(s[a-1])] += 1
    out[a-1].add(b-1)
    out[b-1].add(a-1)
elim = set()
def eliminate(x):
    elim.add(x)
    c = f(s[x])
    for node in out[x]:
        if node not in elim:
            count[node][c] -= 1
            if count[node][0] * count[node][1] == 0:
                eliminate(node)
for i in range(n):
    if i not in elim and count[i][0] * count[i][1] == 0:
        eliminate(i)
if len(elim) < n: print('Yes')
else: print('No')

Fixed submission:
import sys
sys.setrecursionlimit(200000)
n, m = map(int, input().split())
s = input()
out = [set() for _ in range(n)]
count = [[0, 0] for _ in range(n)]
def f(c):
    if c == 'A': return 0
    else: return 1
for _ in range(m):
    a, b = map(int, input().split())
    if a == b:
        count[a-1][f(s[a-1])] += 1
    elif b-1 not in out[a-1]:
        count[a-1][f(s[b-1])] += 1
        count[b-1][f(s[a-1])] += 1
    out[a-1].add(b-1)
    out[b-1].add(a-1)
elim = set()
def eliminate(x):
    elim.add(x)
    c = f(s[x])
    for node in out[x]:
        if node not in elim:
            count[node][c] -= 1
            if count[node][0] * count[node][1] == 0:
                eliminate(node)
for i in range(n):
    if i not in elim and count[i][0] * count[i][1] == 0:
        eliminate(i)
if len(elim) < n: print('Yes')
else: print('No')

Buggy python submission (verdict: Runtime Error):
n, m = map(int, input().split())
s = list(input())
out = [set() for _ in range(n)]
count = [[0, 0] for _ in range(n)]
def f(c):
    if c == 'A': return 0
    else: return 1
for _ in range(m):
    a, b = map(int, input().split())
    if a == b:
        count[a-1][f(s[a-1])] += 1
    elif b-1 not in out[a-1]:
        count[a-1][f(s[b-1])] += 1
        count[b-1][f(s[a-1])] += 1
    out[a-1].add(b-1)
    out[b-1].add(a-1)
elim = set()
def eliminate(x):
    elim.add(x)
    c = f(s[x])
    for node in out[x]:
        if node not in elim:
            count[node][c] -= 1
            if count[node][0] * count[node][1] == 0:
                eliminate(node)
for i in range(n):
    if i not in elim and count[i][0] * count[i][1] == 0:
        eliminate(i)
if len(elim) < n: print('Yes')
else: print('No')

Fixed submission:
import sys
sys.setrecursionlimit(200000)
n, m = map(int, input().split())
s = input()
out = [set() for _ in range(n)]
count = [[0, 0] for _ in range(n)]
def f(c):
    if c == 'A': return 0
    else: return 1
for _ in range(m):
    a, b = map(int, input().split())
    if a == b:
        count[a-1][f(s[a-1])] += 1
    elif b-1 not in out[a-1]:
        count[a-1][f(s[b-1])] += 1
        count[b-1][f(s[a-1])] += 1
    out[a-1].add(b-1)
    out[b-1].add(a-1)
elim = set()
def eliminate(x):
    elim.add(x)
    c = f(s[x])
    for node in out[x]:
        if node not in elim:
            count[node][c] -= 1
            if count[node][0] * count[node][1] == 0:
                eliminate(node)
for i in range(n):
    if i not in elim and count[i][0] * count[i][1] == 0:
        eliminate(i)
if len(elim) < n: print('Yes')
else: print('No')

Buggy python submission (verdict: Runtime Error):
n, m = map(int, input().split())
s = list(input())
out = [set() for _ in range(n)]
count = [[0, 0] for _ in range(n)]
def f(c):
    if c == 'A': return 0
    else: return 1
for _ in range(m):
    a, b = map(int, input().split())
    if a == b:
        count[a-1][f(s[a-1])] += 1
    elif b-1 not in out[a-1]:
        count[a-1][f(s[b-1])] += 1
        count[b-1][f(s[a-1])] += 1
    out[a-1].add(b-1)
    out[b-1].add(a-1)
elim = set()
def eliminate(x):
    elim.add(x)
    c = f(s[x])
    for node in out[x]:
        if node not in elim:
            count[node][c] -= 1
            if count[node][0] * count[node][1] == 0:
                eliminate(node)
for i in range(n):
    if i not in elim and count[i][0] * count[i][1] == 0:
        eliminate(i)
if len(elim) < n: print('Yes')
else: print('No')

Fixed submission:
import sys
sys.setrecursionlimit(200000)
n, m = map(int, input().split())
s = input()
out = [set() for _ in range(n)]
count = [[0, 0] for _ in range(n)]
def f(c):
    if c == 'A': return 0
    else: return 1
for _ in range(m):
    a, b = map(int, input().split())
    if a == b:
        count[a-1][f(s[a-1])] += 1
    elif b-1 not in out[a-1]:
        count[a-1][f(s[b-1])] += 1
        count[b-1][f(s[a-1])] += 1
    out[a-1].add(b-1)
    out[b-1].add(a-1)
elim = set()
def eliminate(x):
    elim.add(x)
    c = f(s[x])
    for node in out[x]:
        if node not in elim:
            count[node][c] -= 1
            if count[node][0] * count[node][1] == 0:
                eliminate(node)
for i in range(n):
    if i not in elim and count[i][0] * count[i][1] == 0:
        eliminate(i)
if len(elim) < n: print('Yes')
else: print('No')

Buggy python submission (verdict: Runtime Error):
n, m = map(int, input().split())
s = list(input())
out = [set() for _ in range(n)]
count = [[0, 0] for _ in range(n)]
def f(c):
    if c == 'A': return 0
    else: return 1
for _ in range(m):
    a, b = map(int, input().split())
    out[a-1].add(b-1)
    out[b-1].add(a-1)
    count[a-1][f(s[b-1])] += 1
    count[b-1][f(s[a-1])] += 1
elim = set()
def eliminate(x, c):
    count[x][c] -= 1
    if count[x][0] & count[x][1] == 0:
        elim.add(x)
        for node in out[x]:
            if node not in elim:
                eliminate(node, f(s[x]))
for i in range(n):
    if count[i][0] & count[i][1] == 0:
        elim.add(i)
        for node in out[i]:
            if node not in elim:
                eliminate(node, f(s[i]))
if len(elim) < n: print('Yes')
else: print('No')

Fixed submission:
import sys
sys.setrecursionlimit(200000)
n, m = map(int, input().split())
s = input()
out = [set() for _ in range(n)]
count = [[0, 0] for _ in range(n)]
def f(c):
    if c == 'A': return 0
    else: return 1
for _ in range(m):
    a, b = map(int, input().split())
    if a == b:
        count[a-1][f(s[a-1])] += 1
    elif b-1 not in out[a-1]:
        count[a-1][f(s[b-1])] += 1
        count[b-1][f(s[a-1])] += 1
    out[a-1].add(b-1)
    out[b-1].add(a-1)
elim = set()
def eliminate(x):
    elim.add(x)
    c = f(s[x])
    for node in out[x]:
        if node not in elim:
            count[node][c] -= 1
            if count[node][0] * count[node][1] == 0:
                eliminate(node)
for i in range(n):
    if i not in elim and count[i][0] * count[i][1] == 0:
        eliminate(i)
if len(elim) < n: print('Yes')
else: print('No')

Buggy python submission (verdict: Time Limit Exceeded):
n, m = map(int, input().split())
s = list(input())
connect = [set() for _ in range(n)]
for _ in range(m):
    a, b = map(int, input().split())
    connect[a-1].add(b-1)
    connect[b-1].add(a-1)
def check(xs):
    a, b = 0, 0
    for x in xs:
        if s[x] == 'A':
            a = 1
        elif s[x] == 'B':
            b = 1
        if a & b:
            return True
    return False
update = True
while update:
    update = False
    for i in range(n):
        if s[i] != 'X':
            if not check(connect[i]):
                update = True
                s[i] = 'X'
if 'A' in s and 'B' in s: print('Yes')
else: print('No')

Fixed submission:
import sys
sys.setrecursionlimit(200000)
n, m = map(int, input().split())
s = input()
out = [set() for _ in range(n)]
count = [[0, 0] for _ in range(n)]
def f(c):
    if c == 'A': return 0
    else: return 1
for _ in range(m):
    a, b = map(int, input().split())
    if a == b:
        count[a-1][f(s[a-1])] += 1
    elif b-1 not in out[a-1]:
        count[a-1][f(s[b-1])] += 1
        count[b-1][f(s[a-1])] += 1
    out[a-1].add(b-1)
    out[b-1].add(a-1)
elim = set()
def eliminate(x):
    elim.add(x)
    c = f(s[x])
    for node in out[x]:
        if node not in elim:
            count[node][c] -= 1
            if count[node][0] * count[node][1] == 0:
                eliminate(node)
for i in range(n):
    if i not in elim and count[i][0] * count[i][1] == 0:
        eliminate(i)
if len(elim) < n: print('Yes')
else: print('No')

Buggy python submission (verdict: Time Limit Exceeded):
n, m = map(int, input().split())
s = list(input())
connect = [set() for _ in range(n)]
for _ in range(m):
    a, b = map(int, input().split())
    connect[a-1].add(b-1)
    connect[b-1].add(a-1)
def reach(xs):
    ret = set()
    for x in xs:
        ret.add(s[x])
    return ret
update = True
while update:
    update = False
    for i in range(n):
        if s[i] != 'X':
            c = reach(connect[i])
            if not ('A' in c and 'B' in c):
                update = True
                s[i] = 'X'
if 'A' in s and 'B' in s: print('Yes')
else: print('No')

Fixed submission:
import sys
sys.setrecursionlimit(200000)
n, m = map(int, input().split())
s = input()
out = [set() for _ in range(n)]
count = [[0, 0] for _ in range(n)]
def f(c):
    if c == 'A': return 0
    else: return 1
for _ in range(m):
    a, b = map(int, input().split())
    if a == b:
        count[a-1][f(s[a-1])] += 1
    elif b-1 not in out[a-1]:
        count[a-1][f(s[b-1])] += 1
        count[b-1][f(s[a-1])] += 1
    out[a-1].add(b-1)
    out[b-1].add(a-1)
elim = set()
def eliminate(x):
    elim.add(x)
    c = f(s[x])
    for node in out[x]:
        if node not in elim:
            count[node][c] -= 1
            if count[node][0] * count[node][1] == 0:
                eliminate(node)
for i in range(n):
    if i not in elim and count[i][0] * count[i][1] == 0:
        eliminate(i)
if len(elim) < n: print('Yes')
else: print('No')

Buggy python submission (verdict: Time Limit Exceeded):
n, m = map(int, input().split())
s = list(input())
connect = [set() for _ in range(n)]
for _ in range(m):
    a, b = map(int, input().split())
    connect[a-1].add(b-1)
    connect[b-1].add(a-1)
def reach(xs):
    ret = set()
    for x in xs:
        ret.add(s[x])
    return ret
update = True
while update:
    update = False
    for i in range(n):
        if s[i] != 'X':
            c = reach(connect[i])
            if not ('A' in c and 'B' in c):
                update = True
                s[i] = 'X'
if 'A' in s and 'B' in s: print('Yes')
else: print('No')

Fixed submission:
import sys
sys.setrecursionlimit(200000)
n, m = map(int, input().split())
s = input()
out = [set() for _ in range(n)]
count = [[0, 0] for _ in range(n)]
def f(c):
    if c == 'A': return 0
    else: return 1
for _ in range(m):
    a, b = map(int, input().split())
    if a == b:
        count[a-1][f(s[a-1])] += 1
    elif b-1 not in out[a-1]:
        count[a-1][f(s[b-1])] += 1
        count[b-1][f(s[a-1])] += 1
    out[a-1].add(b-1)
    out[b-1].add(a-1)
elim = set()
def eliminate(x):
    elim.add(x)
    c = f(s[x])
    for node in out[x]:
        if node not in elim:
            count[node][c] -= 1
            if count[node][0] * count[node][1] == 0:
                eliminate(node)
for i in range(n):
    if i not in elim and count[i][0] * count[i][1] == 0:
        eliminate(i)
if len(elim) < n: print('Yes')
else: print('No')