Buggy python submission (verdict: Time Limit Exceeded):
N,Q=map(int, input().split())
s=input()
td=[input().split() for i in range(Q)]

def move(s,td,position):
    p=position
    for spell in td:
        if s[p]==spell[0] and spell[1]=='L':
            p-=1
        elif s[p]==spell[0] and spell[1]=='R':
            p+=1
        if p<0 or p>=N: break
    return p

l=0
r=N-1
watched=[0]*N
while(True):
    p=(r+l)//2
    if watched[p]>0:
        if p<N-1 and watched[p+1]==0:
            p+=1
        else:
            break
    res=move(s,td,p)
    if res<0:
        l=p
        watched[p]=1
    else:
        r=p
        if watched[p]==0: watched[p]=2
ans_l=N
for i in range(N):
    if watched[i]==2:
        ans_l=i
        break

l=0
r=N-1
watched2=[0]*N
while(True):
    p=(r+l)//2
    if watched2[p]>0:
        if p<N-1 and watched2[p+1]==0:
            p+=1
        else:
            break
    res=move(s,td,p)
    if res>=N:
        r=p
        watched2[p]=3
    else:
        l=p
        if watched2[p]==0: watched2[p]=2
ans_r=0
for i in range(N-1,-1,-1):
    if watched2[i]==2:
        ans_r=i
        break
print(max(0,ans_r-ans_l+1))


Fixed submission:
N,Q=map(int, input().split())
s=input()
td=[input().split() for i in range(Q)]

def move(s,td,position):
    p=position
    for spell in td:
        if s[p]==spell[0] and spell[1]=='L':
            p-=1
        elif s[p]==spell[0] and spell[1]=='R':
            p+=1
        if p<0 or p>=N: break
    return p

l=0
r=N-1
watched=[0]*N
while(True):
    p=(r+l)//2
    if watched[p]>0:
        if p<N-1 and watched[p+1]==0:
            p+=1
        else:
            break
    res=move(s,td,p)
    if res<0:
        l=p
        watched[p]=1
    else:
        r=p
        if watched[p]==0: watched[p]=2
ans_l=N
for i in range(N):
    if watched[i]==2:
        ans_l=i
        break

l=0
r=N-1
watched2=[0]*N
while(True):
    p=(r+l)//2
    if watched2[p]>0:
        if p<N-1 and watched2[p+1]==0:
            p+=1
        else:
            break
    res=move(s,td,p)
    if res>=N:
        r=p
        watched2[p]=3
    else:
        l=p
        if watched2[p]==0: watched2[p]=2
ans_r=-1
for i in range(N-1,-1,-1):
    if watched2[i]==2:
        ans_r=i
        break
print(max(0,ans_r-ans_l+1))

Buggy python submission (verdict: Runtime Error):
N,Q=map(int, input().split())
s=input()
td=[input().split() for i in range(Q)]

l=0
r=len(s)-1
for spell in reversed(td):
    if spell[0]==s[l] and spell[1]=='L':
        l+=1
    elif spell[0]==s[r] and spell[1]=='R':
        r-=1
print(max(0,r-l+1))


Fixed submission:
N,Q=map(int, input().split())
s=input()
td=[input().split() for i in range(Q)]

def move(s,td,position):
    p=position
    for spell in td:
        if s[p]==spell[0] and spell[1]=='L':
            p-=1
        elif s[p]==spell[0] and spell[1]=='R':
            p+=1
        if p<0 or p>=N: break
    return p

l=0
r=N-1
watched=[0]*N
while(True):
    p=(r+l)//2
    if watched[p]>0:
        if p<N-1 and watched[p+1]==0:
            p+=1
        else:
            break
    res=move(s,td,p)
    if res<0:
        l=p
        watched[p]=1
    else:
        r=p
        if watched[p]==0: watched[p]=2
ans_l=N
for i in range(N):
    if watched[i]==2:
        ans_l=i
        break

l=0
r=N-1
watched2=[0]*N
while(True):
    p=(r+l)//2
    if watched2[p]>0:
        if p<N-1 and watched2[p+1]==0:
            p+=1
        else:
            break
    res=move(s,td,p)
    if res>=N:
        r=p
        watched2[p]=3
    else:
        l=p
        if watched2[p]==0: watched2[p]=2
ans_r=-1
for i in range(N-1,-1,-1):
    if watched2[i]==2:
        ans_r=i
        break
print(max(0,ans_r-ans_l+1))

Buggy python submission (verdict: Time Limit Exceeded):
N,Q=map(int, input().split())
s=input()
td=[input().split() for i in range(Q)]

import numpy as np

S=[np.zeros(N,dtype=np.int) for i in range(26)]
for p,c in enumerate(s):
    for i in range(26):
        if i==ord(c)-65:
            S[i][p]=1

g=np.ones(N,dtype=np.int)
for q in td:
    g_stable=g*np.logical_not(S[ord(q[0])-65])
    if q[1]=='L':
        g_move=np.append((g*S[ord(q[0])-65])[1:],0)
    else:
        g_move=np.insert((g*S[ord(q[0])-65])[:-1],0,0)
    g=g_stable+g_move
print(np.sum(g))

Fixed submission:
N,Q=map(int, input().split())
s=input()
td=[input().split() for i in range(Q)]

def move(s,td,position):
    p=position
    for spell in td:
        if s[p]==spell[0] and spell[1]=='L':
            p-=1
        elif s[p]==spell[0] and spell[1]=='R':
            p+=1
        if p<0 or p>=N: break
    return p

l=0
r=N-1
watched=[0]*N
while(True):
    p=(r+l)//2
    if watched[p]>0:
        if p<N-1 and watched[p+1]==0:
            p+=1
        else:
            break
    res=move(s,td,p)
    if res<0:
        l=p
        watched[p]=1
    else:
        r=p
        if watched[p]==0: watched[p]=2
ans_l=N
for i in range(N):
    if watched[i]==2:
        ans_l=i
        break

l=0
r=N-1
watched2=[0]*N
while(True):
    p=(r+l)//2
    if watched2[p]>0:
        if p<N-1 and watched2[p+1]==0:
            p+=1
        else:
            break
    res=move(s,td,p)
    if res>=N:
        r=p
        watched2[p]=3
    else:
        l=p
        if watched2[p]==0: watched2[p]=2
ans_r=-1
for i in range(N-1,-1,-1):
    if watched2[i]==2:
        ans_r=i
        break
print(max(0,ans_r-ans_l+1))

Buggy python submission (verdict: Time Limit Exceeded):
N,Q=map(int, input().split())
s=input()
td=[input().split() for i in range(Q)]

import numpy as np

S=[np.zeros(N) for i in range(26)]
for p,c in enumerate(s):
    for i in range(26):
        if i==ord(c)-65:
            S[i][p]=1
S1=np.ones(N)

from functools import reduce
g=np.ones(N)
for q in td:
    g_stable=g*np.logical_not(S[ord(q[0])-65])
    if q[1]=='L':
        g_move=np.append((g*S[ord(q[0])-65])[1:],0)
    else:
        g_move=np.insert((g*S[ord(q[0])-65])[:-1],0,0)
    g=g_stable+g_move
print(int(np.sum(g)))

Fixed submission:
N,Q=map(int, input().split())
s=input()
td=[input().split() for i in range(Q)]

def move(s,td,position):
    p=position
    for spell in td:
        if s[p]==spell[0] and spell[1]=='L':
            p-=1
        elif s[p]==spell[0] and spell[1]=='R':
            p+=1
        if p<0 or p>=N: break
    return p

l=0
r=N-1
watched=[0]*N
while(True):
    p=(r+l)//2
    if watched[p]>0:
        if p<N-1 and watched[p+1]==0:
            p+=1
        else:
            break
    res=move(s,td,p)
    if res<0:
        l=p
        watched[p]=1
    else:
        r=p
        if watched[p]==0: watched[p]=2
ans_l=N
for i in range(N):
    if watched[i]==2:
        ans_l=i
        break

l=0
r=N-1
watched2=[0]*N
while(True):
    p=(r+l)//2
    if watched2[p]>0:
        if p<N-1 and watched2[p+1]==0:
            p+=1
        else:
            break
    res=move(s,td,p)
    if res>=N:
        r=p
        watched2[p]=3
    else:
        l=p
        if watched2[p]==0: watched2[p]=2
ans_r=-1
for i in range(N-1,-1,-1):
    if watched2[i]==2:
        ans_r=i
        break
print(max(0,ans_r-ans_l+1))