Buggy python submission (verdict: Time Limit Exceeded):
import sys
input = sys.stdin.readline

S = list(reversed(list(input().strip())))
P = [list(reversed(v)) for v in ["dream", "dreamer", "erase", "eraser"]]

sys.setrecursionlimit(10000)
def dfs(n):
    if len(S[n:]) == 0:
        return True
    
    for v in P:
        if S[n:n+len(v)] == v:
            if dfs(n + len(v)):
                return True
    
    return False

if dfs(0):
    print("YES")
else:
    print("NO")


Fixed submission:
import sys
input = sys.stdin.readline

S = list(reversed(input().strip()))
P = [list(reversed(v)) for v in ["dream", "dreamer", "erase", "eraser"]]

n = 0
while n < len(S):
    if S[n:n+5] == P[0] or S[n:n+5] == P[2]:
        n += 5
    elif S[n:n+7] == P[1]:
        n += 7
    elif S[n:n+6] == P[3]:
        n += 6
    else:
        print("NO")
        exit()
        
print("YES")

Buggy python submission (verdict: Runtime Error):
import sys
from collections import deque
input = sys.stdin.readline

S = list(input().strip())
P = [list(v) for v in ["dream", "dreamer", "erase", "eraser"]]

n = 0
i = 0
his = deque()
while True:
    v = P[i]
    
    p = S[n:n+len(v)]
    if p == v:
        xx = S[n+len(v):]
        if xx == []:
            print("YES")
            exit()
        else:
            his.append([n, i + 1])
            n += len(v)
            i = 0
    else:
        i += 1
        if i == 4:
            if len(his) == 0:
                break
            else:
                n, i = his.pop()
                
print("NO")

Fixed submission:
import sys
input = sys.stdin.readline

S = list(reversed(input().strip()))
P = [list(reversed(v)) for v in ["dream", "dreamer", "erase", "eraser"]]

n = 0
while n < len(S):
    if S[n:n+5] == P[0] or S[n:n+5] == P[2]:
        n += 5
    elif S[n:n+7] == P[1]:
        n += 7
    elif S[n:n+6] == P[3]:
        n += 6
    else:
        print("NO")
        exit()
        
print("YES")

Buggy python submission (verdict: Time Limit Exceeded):
import sys
input = sys.stdin.readline

S = list(input().strip())
P = [list(v) for v in ["dream", "dreamer", "erase", "eraser"]]

sys.setrecursionlimit(10000)
def dfs(n):
    if len(S[n:]) == 0:
        return True
    
    for v in P:
        if S[n:n+len(v)] == v:
            if dfs(n + len(v)):
                return True
    
    return False

if dfs(0):
    print("YES")
else:
    print("NO")

Fixed submission:
import sys
input = sys.stdin.readline

S = list(reversed(input().strip()))
P = [list(reversed(v)) for v in ["dream", "dreamer", "erase", "eraser"]]

n = 0
while n < len(S):
    if S[n:n+5] == P[0] or S[n:n+5] == P[2]:
        n += 5
    elif S[n:n+7] == P[1]:
        n += 7
    elif S[n:n+6] == P[3]:
        n += 6
    else:
        print("NO")
        exit()
        
print("YES")

Buggy python submission (verdict: Time Limit Exceeded):
import sys
input = sys.stdin.readline

S = list(input().strip())
P = [list(v) for v in ["dream", "dreamer", "erase", "eraser"]]

sys.setrecursionlimit(10000)
def dfs(n):
    if len(S[n:]) == 0:
        return True
    
    for v in P:
        if S[n:n+len(v)] == v:
            if dfs(n + len(v)):
                return True
    
    return False

if dfs(0):
    print("YES")
else:
    print("NO")

Fixed submission:
import sys
input = sys.stdin.readline

S = list(reversed(input().strip()))
P = [list(reversed(v)) for v in ["dream", "dreamer", "erase", "eraser"]]

n = 0
while n < len(S):
    if S[n:n+5] == P[0] or S[n:n+5] == P[2]:
        n += 5
    elif S[n:n+7] == P[1]:
        n += 7
    elif S[n:n+6] == P[3]:
        n += 6
    else:
        print("NO")
        exit()
        
print("YES")

Buggy python submission (verdict: Runtime Error):
import sys
input = sys.stdin.readline

S = list(input().strip())
P = [list(v) for v in ["dream", "dreamer", "erase", "eraser"]]

def dfs(n):
    if len(S[n:]) == 0:
        return True
    
    for v in P:
        if S[n:n+len(v)] == v:
            if dfs(n + len(v)):
                return True
    
    return False

if dfs(0):
    print("YES")
else:
    print("NO")

Fixed submission:
import sys
input = sys.stdin.readline

S = list(reversed(input().strip()))
P = [list(reversed(v)) for v in ["dream", "dreamer", "erase", "eraser"]]

n = 0
while n < len(S):
    if S[n:n+5] == P[0] or S[n:n+5] == P[2]:
        n += 5
    elif S[n:n+7] == P[1]:
        n += 7
    elif S[n:n+6] == P[3]:
        n += 6
    else:
        print("NO")
        exit()
        
print("YES")