qyliang/CodeNanoFix huggingface dataset:
Buggy code:

if input().rstrip().replace("dream","D").replace("erase","E").replace("Der","").replace("Eer","").replace("D","").replace("E","") == "":
    print( "YES" )
else:
    print( "NO" )


Fixed code:
if input().rstrip().replace("dream","D").replace("erase","E").replace("Der","").replace("Er","").replace("D","").replace("E","") == "":
    print( "YES" )
else:
    print( "NO" )
Buggy code:
S = input()[::-1]

while len(S) > 0:
    if S[:5] == 'maerd':
        S = S[:5]
    elif S[:5] == 'esare':
        S = S[5:]
    elif S[:6] == 'resare':
        S = S[6:]
    elif S[:7] == 'remaerd':
        S = S[7:]
    else:
        print('NO')

if len(S) == 0:
    print('YES')


Fixed code:
S = input()[::-1]

while len(S) > 0:
    if S[:5] == 'maerd':
        S = S[5:]
    elif S[:5] == 'esare':
        S = S[5:]
    elif S[:6] == 'resare':
        S = S[6:]
    elif S[:7] == 'remaerd':
        S = S[7:]
    else:
        print('NO')
        break

if len(S) == 0:
    print('YES')
Buggy code:
s=input()
s=s.replace("eraser","")
s=s.replace("erase","")
s=s.replace("dreamer","")
s=s.replace("dream,","")
if s:
    print("NO")
else:
    print("YES")

Fixed code:
s = str(input())

s = s.replace("eraser","")
s = s.replace("erase","")
s = s.replace("dreamer","")
s = s.replace("dream","")

if s == "" :
    print("YES")
else:
    print("NO")
Buggy code:
s = input()
s.replace("eraser","").replace("erase","").replace("dreamer","").replace("dream","")
print("YES") if s == "" else print("NO")

Fixed code:
s=input()
if ""==s.replace("eraser","").replace("erase","").replace("dreamer","").replace("dream",""):
  print("YES")
else:
  print("NO")
Buggy code:
S = input()

if S.replace("dream",).replace("dreamer",).replace.("erase",).replace("eraser",):
  print("NO")
else:
  print("YES")

Fixed code:
S = input()

if S.replace("eraser","").replace("erase","").replace("dreamer","").replace("dream",""):
  print("NO")
else:
  print("YES")
Buggy code:
S = input()

candidates = ["dream", "dreamer", "erase", "eraser"]

find_flag = 0
rest_S = S
while True:
#    print(rest_S, rest_S[-6:], rest_S[-7:]) 
    if len(rest_S) == 0:
        find_flag = 1
        break
    elif rest_S[-6:] in candidates:
        rest_S = rest_S[:-6]
    elif rest_S[-7:] in candidates:
        rest_S = rest_S[:-7]
    else:
        break

if find_flag:
    print("YES")
else:
    print("NO")

Fixed code:
S = input()

candidates = ["dream", "dreamer", "erase", "eraser"]

find_flag = 0
rest_S = S
while True:
#     print(rest_S[-5:], rest_S[-7:]) 
    if len(rest_S) == 0:
        find_flag = 1
        break
    elif (len(rest_S) >= 7) & (rest_S[-7:] in candidates):
        rest_S = rest_S[:-7]
    elif (len(rest_S) >= 6) & (rest_S[-6:] in candidates):
        rest_S = rest_S[:-6]
    elif (len(rest_S) >= 5) & (rest_S[-5:] in candidates):
        rest_S = rest_S[:-5]
    else:
        break

if find_flag:
    print("YES")
else:
    print("NO")
Buggy code:
import math
import numpy as np


#a, b, c, x = map(int, [input() for i in range(4)])
#z = list(map(int, input().split()))
#n, a, b = map(int, input().split())

#print(len(z))
#for i in z:
#    print(i)

#a = sorted(a,reverse = True)
#print(sum(a[::2]) - sum(a[1::2]))
#z = map(int, [input() for i in range(int(n))])

s = input()

s.replace("eraser","").replace("erase","").replace("dreamer","").replace("dream","")

if s:
    print("NO")
else:
    print("YES")


Fixed code:
import math
import numpy as np


#a, b, c, x = map(int, [input() for i in range(4)])
#z = list(map(int, input().split()))
#n, a, b = map(int, input().split())

#print(len(z))
#for i in z:
#    print(i)

#a = sorted(a,reverse = True)
#print(sum(a[::2]) - sum(a[1::2]))
#z = map(int, [input() for i in range(int(n))])

s = input()

s = s.replace("eraser","").replace("erase","").replace("dreamer","").replace("dream","")


if s:
    print("NO")
else:
    print("YES")
Buggy code:
s=input().replace("dream","").replace("erase","").replace("eraser","").replace("dreamer","")
print("YES" if len(s)==0 else "NO")

Fixed code:
s=input().replace("eraser","").replace("erase","").replace("dreamer","").replace("dream","")
print("YES" if len(s)==0 else "NO")
Buggy code:
s=input().replace("erase","").replace("dream",""),replace("eraser","").replace("dreamer","")
if s in "":
    print("YES")
else:
    print("NO")


Fixed code:
s=input().replace("eraser","").replace("erase","").replace("dreamer","").replace("dream","")
if s in "":
    print("YES")
else:
    print("NO")
Buggy code:
s=input().replace("eraser",",").replace("eraser",",").replace("dreamer",",").replace("dream",",").replace(",","")
print("YES" if s=="" else "NO")


Fixed code:
s=input().replace("eraser",",").replace("erase",",").replace("dreamer",",").replace("dream",",").replace(",","")
print("YES" if s=="" else "NO")
Buggy code:
s = input()
s = s.replace('dreamer', '')
s = s.replace('dream', '')
s = s.replace('eraser', '')
s = s.replace('erase', '')
if s == '':
    print('YES')
else:
    print('NO')

Fixed code:
s = input()
s = s.replace('eraser', '')
s = s.replace('erase', '')
s = s.replace('dreamer', '')
s = s.replace('dream', '')
if s == '':
    print('YES')
else:
    print('NO')
Buggy code:
s="dreamerer"

s=s.replace('eraser','').replace('erase','').replace('dreamer','').replace('dream','')

if len(s)==0:print("YES")
else:print("NO")    


Fixed code:
s=input()
s=s.replace('eraser','0').replace('erase','0').replace('dreamer','0').replace('dream','0')
s=s.replace('0','')

if len(s)==0:print("YES")
else:print("NO")
Buggy code:
S = input()

while True:
    if len(S) == 0:
        print('YES')
        break
    else:
        if S[-5:]=='dream':
            S = S[:-5]
        elif S[-7:] == 'dreamer':
            S = S[:-7]
        elif S[-5:]== 'erase':
            S = S[:-5]
        elif S[-6:] == X4:
            S = S[:-6]
        else:
            print('NO')
            break


Fixed code:
S = input()

while True:
    if len(S) == 0:
        print('YES')
        break
    else:
        if S[-5:]=='dream':
            S = S[:-5]
        elif S[-7:] == 'dreamer':
            S = S[:-7]
        elif S[-5:]== 'erase':
            S = S[:-5]
        elif S[-6:] == 'eraser':
            S = S[:-6]
        else:
            print('NO')
            break
Buggy code:
S=input()
n=0
#print(S)
while S[:]!=S[:n]:
    if S[n:n+5]=="dream" and S[n:n+7]!="dreamer":
        n+=5
    elif S[n:n+7]=="dreamer":
        n+=7
    elif S[n:n+5]=="erase" and S[n+6]!="eraser":
        n+=5
    elif S[n:n+6]=="eraser":
        n+=6
    #elif S[:]==S[:n-1]:
        #print("YES")
        #exit()
    else:
        print("NO")
        exit()
else:
    print("YES")

Fixed code:
S=input()
n=0
#print(S)
while S[:]!=S[:n]:
    if S[n:n+7]=="dreamer" and S[n:n+8]!="dreamera":
        n+=7 #dreamer
    elif S[n:n+5]=="dream":
        n+=5 #dream
    elif S[n:n+5]=="erase" and S[n:n+6]!="eraser":
        n+=5 #erase
    elif S[n:n+6]=="eraser":
        n+=6 #eraser
    #elif S[:]==S[:n-1]:
        #print("YES")
        #exit()
    else:
        print("NO")
        exit()
else:
    print("YES")
Buggy code:
s = input()
s_rev = s[::-1]
while s_rev[0:1]:
    if s_rev.startswith("maerd"):
        s_rev = s_rev[5::1]
    elif s_rev.startswith("remaerd"):
        s_rev = s_rev[7::1]
    elif s_rev.startswith("esare"):
        s_rev = s_rev[5::1]
    elif s_rev.startswith("resare"):
        s_rev = s_rev[6::1]
    else:
        print("NO")
        break
if s_rev[0:1]==False:
    print("YES")

Fixed code:
s = input()
s_rev = s[::-1]
while s_rev[0:1]:
    if s_rev.startswith("maerd"):
        s_rev = s_rev[5::1]
    elif s_rev.startswith("remaerd"):
        s_rev = s_rev[7::1]
    elif s_rev.startswith("esare"):
        s_rev = s_rev[5::1]
    elif s_rev.startswith("resare"):
        s_rev = s_rev[6::1]
    else:
        print("NO")
        break
if bool(s_rev[0:1]) == False:
    print("YES")
Buggy code:
s = 'dreameraser'##input()
l = ['dream', 'dreamer', 'erase', 'eraser']
pos = 0
flg = True
can = False
while flg:
    flg = False
    for i in range(len(l)):
        st = len(l[i])+pos
        if st<=len(s):
            if s[st*(-1):len(s)-pos] == l[i]:
                pos += len(l[i])
                if pos == len(s):
                    can = True
                    break
                flg = True
if can == True:
    print('YES')
else:
    print('NO')


Fixed code:
s = input()
l = ['dream', 'dreamer', 'erase', 'eraser']
pos = 0
flg = True
can = False
while flg:
    flg = False
    for i in range(len(l)):
        st = len(l[i])+pos
        if st<=len(s):
            if s[st*(-1):len(s)-pos] == l[i]:
                pos += len(l[i])
                if pos == len(s):
                    can = True
                    break
                flg = True
if can == True:
    print('YES')
else:
    print('NO')
Buggy code:
s = input()
i = len(s) - 1
flag = False
while i > 0:
    flag = False
    if s[i] == "m" and s[i - 4:i + 1] == "dream":
        flag = True
        i -= 5
    elif s[i] == "e" and s[i - 4: i + 1] == "erase":
        i -= 5
        flag = True
    elif s[i] == "r":
        if s[i - 5: i + 1] == "eraser":
            flag = True
            i -= 6
        elif s[i - 6: i + 1] == "dreamer":
            flag = True
            i -= 7
    if flag == False:
        break
print("Yes" if flag else "No")

Fixed code:
s = input()
i = len(s) - 1
flag = False
while i > 0:
    flag = False
    if s[i] == "m" and s[i - 4:i + 1] == "dream":
        flag = True
        i -= 5
    elif s[i] == "e" and s[i - 4: i + 1] == "erase":
        i -= 5
        flag = True
    elif s[i] == "r":
        if s[i - 5: i + 1] == "eraser":
            flag = True
            i -= 6
        elif s[i - 6: i + 1] == "dreamer":
            flag = True
            i -= 7
    if flag == False:
        break
print("YES" if flag else "NO")
Buggy code:
s=input()
s=s.replace('dream','').replace('dreamer','').replace('erase','').replace('eraser','')
if s:print('NO')
else:print('YES')

Fixed code:
s = input().replace("eraser", "").replace("erase", "").replace("dreamer", "").replace("dream", "")
if s:
    print('NO')
else:
    print('YES')
Buggy code:
target = input()

while len(target)>=5:
    if target[-7:] == "dreamer":
        target = target[:-7]
    elif target[-6:] == "eraser":
        target = target[:-6]
    elif target[-5:]=="dream" or target[-5:]=="erase":
        target = target[:-5]
if len(target)==0:
    print("YES")
else:
    print("NO")

Fixed code:
target = input()

while len(target)>=5:
    if target[-7:] == "dreamer":
        target = target[:-7]
    elif target[-6:] == "eraser":
        target = target[:-6]
    elif target[-5:]=="dream" or target[-5:]=="erase":
        target = target[:-5]
    else:
      break
if len(target)==0:
    print("YES")
else:
    print("NO")
Buggy code:
from sys import stdin
data = stdin.readline().rstrip()

def shorten_phrase(x):
    l = len(x)
    if x.startswith("eraser"):
        x = x[6:]
    elif x.startswith("erase"):
        x = x[5:]
    elif x.startswith("dreamera"):
        x = x[5:]
    elif x.startswith("dreamer"):
        x = x[7:]
    elif x.startswith("dream"):
        x = x[5:]
    m = len(x)
    return l != m

while shorten_phrase(data):
    if data.startswith("eraser"):
        data = data[6:]
    elif data.startswith("erase"):
        data = data[5:]
    elif data.startswith("dreamera"):
        data = data[5:]
    elif data.startswith("dreamer"):
        data = data[7:]
    elif data.startswith("dream"):
        data = data[5:]
if len(data) == 0:
    print("YES")
else:
    print("NO")
print(data)

Fixed code:
from sys import stdin
data = stdin.readline().rstrip()

def shorten_phrase(x):
    l = len(x)
    if x.startswith("eraser"):
        x = x[6:]
    elif x.startswith("erase"):
        x = x[5:]
    elif x.startswith("dreamera"):
        x = x[5:]
    elif x.startswith("dreamer"):
        x = x[7:]
    elif x.startswith("dream"):
        x = x[5:]
    m = len(x)
    return l != m

while shorten_phrase(data):
    if data.startswith("eraser"):
        data = data[6:]
    elif data.startswith("erase"):
        data = data[5:]
    elif data.startswith("dreamera"):
        data = data[5:]
    elif data.startswith("dreamer"):
        data = data[7:]
    elif data.startswith("dream"):
        data = data[5:]
if len(data) == 0:
    print("YES")
else:
    print("NO")
Buggy code:
import sys

stdin = sys.stdin

ni = lambda: int(ns())
na = lambda: list(map(int, stdin.readline().split()))
ns = lambda: stdin.readline().strip()

s = ns()
length = len(s)
flag = 1
while length != 0:
    if s[-5:] == "dream" or s[-5:] == "erase":
        length -= 5
    elif s[-6:] == "eraser":
        length -= 6
    elif s[-7:] == "dreamer":
        length -= 7
    else:
        flag = 0
        break

if flag:
    print("YES")
else:
    print("NO")


Fixed code:
import sys

stdin = sys.stdin

ni = lambda: int(ns())
na = lambda: list(map(int, stdin.readline().split()))
ns = lambda: stdin.readline().strip()

s = ns()
s = list(s)
flag = 1
while len(s) != 0:
    if s[-5:] == list("dream") or s[-5:] == list("erase"):
        del s[-5:]
        continue
    elif s[-6:] == list("eraser"):
        del s[-6:]
        continue
    elif s[-7:] == list("dreamer"):
        del s[-7:]
        continue
    else:
        flag = 0
        break

if flag:
    print("YES")
else:
    print("NO")
Buggy code:
S = input()
Srev = S[::-1]
 
if Srev.startswith('maerd'):
  Srev = Srev[5::]
  continue
elif Srev.startswith('remaerd'):
  Srev = Srev[7::]
  continue
elif Srev.startswith('esare'):
  Srev = Srev[5::]
  continue
elif Srev.startswith('resare'):
  Srev = Srev[6::]
  continue
elif Srev == '':
  print('YES')
  break
else:
  print('NO')
  break

Fixed code:
S = input()
Srev = S[::-1]
while True: 
  if Srev.startswith('maerd'):
    Srev = Srev[5::]
    continue
  elif Srev.startswith('remaerd'):
    Srev = Srev[7::]
    continue
  elif Srev.startswith('esare'):
    Srev = Srev[5::]
    continue
  elif Srev.startswith('resare'):
    Srev = Srev[6::]
    continue
  elif Srev == '':
    print('YES')
    break
  else:
    print('NO')
    break
Buggy code:
s=input()
s.replace("dream","").replace("dreamer","").replace("erase","").replace("eraser","")
if  s:
    print("YES")
else:
    print("NO")

Fixed code:
s = input().replace('eraser', '').replace('erase', '').replace('dreamer', '').replace('dream', '')
if s == '':
    print('YES')
else:
    print('NO')
Buggy code:
# import numpy as np
# import math
# import copy
# from collections import deque
import sys
input = sys.stdin.readline
# sys.setrecursionlimit(10000)


def main():
    S = input().rstrip()

    words = ['dream','dreamer','erase','eraser']

    res = 'YES'

    pre = S
    now = S

    while True:
        for i in range(4):
            word = words[i]
            N = len(word)
            M = len(now)
            if N <= M:
                # l = now[:N]
                r = now[M-N:]
                # if l == word:
                    # now = now[N:]
                if r == word:
                    now = now[:M-N]
            print(now)
        if now == '':
            break
        elif now == pre:
            res = 'NO'
            break
        else:
            pre = now

    print(res)



main()


Fixed code:
# import numpy as np
# import math
# import copy
# from collections import deque
import sys
input = sys.stdin.readline
# sys.setrecursionlimit(10000)


def main():
    S = input().rstrip()

    words = ['dream','dreamer','erase','eraser']

    res = 'YES'

    pre = S
    now = S

    while True:
        for i in range(4):
            word = words[i]
            N = len(word)
            M = len(now)
            if N <= M:
                r = now[M-N:]
                if r == word:
                    now = now[:M-N]
        if now == '':
            break
        elif now == pre:
            res = 'NO'
            break
        else:
            pre = now

    print(res)



main()
Buggy code:
S = list(input())
#S = list("dream" * 20000)
string = [list("dream") ,  list("dreamer") , list("erase") ,list("eraser")]
for i in range(4):
    string[i] = string[i][::-1]
#print(string)
S = S[::-1]
#print(S[0:5])
idx = 0
print(S[idx:5])
while idx != len(S):
    if S[idx:idx + 5] == string[0]:
        idx += 5
    elif S[idx:idx + 7] == string[1]:
        idx += 7
    elif S[idx:idx + 5] == string[2]:
        idx += 5
    elif S[idx:idx + 6] == string[3]:
        idx += 6
    else:
        print("NO")
        exit()
print("YES")

Fixed code:
S = list(input())
#S = list("dream" * 20000)
string = [list("dream") ,  list("dreamer") , list("erase") ,list("eraser")]
for i in range(4):
    string[i] = string[i][::-1]
#print(string)
S = S[::-1]
#print(S[0:5])
idx = 0
#print(S[idx:5])
while idx != len(S):
    if S[idx:idx + 5] == string[0]:
        idx += 5
    elif S[idx:idx + 7] == string[1]:
        idx += 7
    elif S[idx:idx + 5] == string[2]:
        idx += 5
    elif S[idx:idx + 6] == string[3]:
        idx += 6
    else:
        print("NO")
        exit()
print("YES")
Buggy code:
def check(s: str):
  if len(s) >= 5 and s[-5:] in ['dream', 'erase']:
    return s[:-5]
  elif len(s) >= 6 and s[-6:] in ['eraser']:
    return s[:-6]
  elif len(s) >= 7 and s[-7:] in ['dreamer']:
    return s[:-7]
  return None

s = input()
matched = True
while len(s) > 0:
  s = check(s)
  if s is None:
    matched = False
    break
if matched:
  print('Yes')
else:
  print('No')

Fixed code:
def check(s: str):
  if len(s) >= 5 and s[-5:] in ['dream', 'erase']:
    return s[:-5]
  elif len(s) >= 6 and s[-6:] in ['eraser']:
    return s[:-6]
  elif len(s) >= 7 and s[-7:] in ['dreamer']:
    return s[:-7]
  return None

s = input()
matched = True
while len(s) > 0:
  s = check(s)
  if s is None:
    matched = False
    break
if matched:
  print('YES')
else:
  print('NO')
Buggy code:
s=input()

words=['eraser', 'erase', 'dreamer', 'dream']

for w in words:
  s=s.strip(w)

if len(s) != 0:
  print('NO')
else:
  print('YES')

Fixed code:
s=input()

words=['eraser', 'erase', 'dreamer', 'dream']

for w in words:
  s=s.replace(w, '')

if len(s) != 0:
  print('NO')
else:
  print('YES')
Buggy code:
s = str(input())
a = ['dream', 'dreamer', 'erase', 'eraser']

f = True
while f:
    os = s
    for i in a:
        if s.endswith(i):
            s = s[:-len(i)]
            if len(s) == 0:
                print("YES")
                f = False
    if len(os) == len(s):
        print("No")
        f = False

Fixed code:
s = str(input())
a = ['dream', 'dreamer', 'erase', 'eraser']

f = True
while f:
    os = s
    for i in a:
        if s.endswith(i):
            s = s[:-len(i)]
            if len(s) == 0:
                print("YES")
                f = False
    if len(os) == len(s):
        print("NO")
        f = False
Buggy code:
s=input()
s=s.replace('dream', '')
s=s.replace('dreamer', '')
s=s.replace('erase', '')
s=s.replace('eraser', '')

if s=="":
    print("YES")
else:
    print("NO")

Fixed code:
s=input()
s=s.replace("eraser","")
s=s.replace("erase","")
s=s.replace("dreamer","")
s=s.replace("dream","")
if len(s)==0: print("YES")
else: print("NO")
Buggy code:
s=input()
L=len(s)
newstring=''.join(list(reversed(s)))

while L>0:
    if newstring[:5]=="maerd":
        newstring=newstring[5:]

    elif newstring[:7]=="remaerd":
        newstring=newstring[7:]

    elif newstring[:5]=="esare":
        newstring=newstring[5:]

    elif newstring[:6]=="resare":
        newstring=newstring[6:]

    else:
        print("NO")
        exit()

print("YES")

Fixed code:
s=input()
newstring=''.join(list(reversed(s)))

while len(newstring)>0:
    if newstring[:5]=="maerd":
        newstring=newstring[5:]

    elif newstring[:7]=="remaerd":
        newstring=newstring[7:]

    elif newstring[:5]=="esare":
        newstring=newstring[5:]

    elif newstring[:6]=="resare":
        newstring=newstring[6:]

    else:
        print("NO")
        exit()

print("YES")
Buggy code:
s = input()
s_rev = s[::-1]
T_list = ['maerd', 'remaerd', 'esare', 'resare']

def mojicut(s, r):
    n = s.replace(r, "", 1)
    return n


while len(s_rev) > 0:
    s_len = len(s_rev)
    for i in T_list:
        if s_rev.startswith(i):
            s_rev = mojicut(s_rev, i)
            break
    if len(s_rev) == s_len:
        break

if len(s_rev) > 0:
    print("No")
else:
    print("Yes")



Fixed code:
s = input()
s_rev = s[::-1]
T_list = ['maerd', 'remaerd', 'esare', 'resare']
 
def mojicut(s, r):
    n = s.replace(r, "", 1)
    return n
 
 
while len(s_rev) > 0:
    s_len = len(s_rev)
    for i in T_list:
        if s_rev.startswith(i):
            s_rev = mojicut(s_rev, i)
            break
    if len(s_rev) == s_len:
        break
 
if len(s_rev) > 0:
    print("NO")
else:
    print("YES")
Buggy code:
s=input()
s.replace("eraser","")
s.replace("erase","")
s.replace("dreamer","")
s.replace("dream","")

if len(s)==0: print("YES")
else: print("NO")

Fixed code:
S=input()
S=S.replace("eraser","")
S=S.replace("erase","")
S=S.replace("dreamer","")
S=S.replace("dream","")
if len(S)==0:
  print("YES")
else:
  print("NO")
Buggy code:
s = input()[::-1]
words = ['maerd', 'remaerd', 'esare', 'resare']
flag = 0
for _ in range(25000):
    if flag==4:
        break
    else:
        flag=0
    for word in words:
        l = len(word)
        if s[0:l] == word:
            s = s[l:]
        else:
            flag+=1
if flag==4:
    print('NO')
else:
    print('YES')

Fixed code:
s = input()[::-1]
words = ['maerd', 'remaerd', 'esare', 'resare']
flag = 0
for _ in range(25000):
    if flag==4 or len(s)==0:
        break
    else:
        flag=0
    for word in words:
        l = len(word)
        if s[0:l] == word:
            s = s[l:]
        else:
            flag+=1
if flag==4:
    print('NO')
else:
    print('YES')
Buggy code:
s=input()[::-1]
i=0
while i<len(s):
    if i+5<=len(s) and s[i:i+5]=='rsare':
        i+=5
    elif i+5<=len(s) and s[i:i+5]=='maerd':
        i+=5
    elif i+6<=len(s) and s[i:i+6]=='resare':
        i+=6
    elif i+7<=len(s) and s[i:i+7]=='remaerd':
        i+=7
    elif i<len(s):
        print('NO')
        exit()
print('YES')

Fixed code:
s=input()[::-1]
i=0
while i<len(s):
    if i+5<=len(s) and s[i:i+5]=='esare':
        i+=5
    elif i+5<=len(s) and s[i:i+5]=='maerd':
        i+=5
    elif i+6<=len(s) and s[i:i+6]=='resare':
        i+=6
    elif i+7<=len(s) and s[i:i+7]=='remaerd':
        i+=7
    elif i<len(s):
        print('NO')
        exit()
print('YES')
Buggy code:
from collections import deque
import sys

def fnw(n,s):
    sm=deque([])
    if n<=len(s):
        for _ in range(n):
            sm.append(s.popleft())
    return ''.join(sm)

def jfws(s):
    fws=fnw(5,s)
    if fws=='dream':
        fws=fnw(2,s)
        if fws=='er':
            if s[0]=='a':
                s.extendleft(deque(reversed(list(fws))))
        else:
            s.extendleft(deque(reversed(list(fws))))
        return False
    elif fws=='erase':
        fws=fnw(1,s)
        if fws!='r':
            s.appendleft(fws)
        return False
    else:
        return True 

def main(s):
    while True:
        if jfws(s):
            return 'NO'
        if not bool(s):
            return 'Yes'

s=deque(sys.stdin.readline().strip())
print(main(s))



Fixed code:
from collections import deque
import sys

def fnw(n,s):
    sm=deque([])
    if n<=len(s):
        for _ in range(n):
            sm.append(s.popleft())
    return ''.join(sm)

def jfws(s):
    fws=fnw(5,s)
    if fws=='dream':
        fws=fnw(2,s)
        if fws=='er':
            if s:
                if s[0]=='a':
                    s.extendleft(deque(reversed(list(fws))))
        else:
            s.extendleft(deque(reversed(list(fws))))
        return False
    elif fws=='erase':
        fws=fnw(1,s)
        if fws!='r' and fws!='':
            s.appendleft(fws)
        return False
    else:
        return True 

def main(s):
    while s:
        if jfws(s):
            return 'NO'
    return 'YES'

s=deque(sys.stdin.readline().strip())
print(main(s))