Buggy python submission (verdict: Runtime Error):
s1 = "maerd"
s2 = "remaerd"
s3 = "esare"
s4 = "resare"

i = input()
s = ''
for c in reversed(i):
    s += c

l = len(s)

i = 0


def dfs(i):
    if i == l:
        print("YES")
        exit()
    if i+5 <= l and s[i:i+5] == s1:
        dfs(i+5)
    elif i+7 <= l and s[i:i+7] == s2:
        dfs(i+7)
    elif i+5 <= l and s[i:i+5] == s3:
        dfs(i+5)
    elif i+6 <= l and s[i:i+6] == s4:
        dfs(i+6)
    else:
        print("NO")
        exit()


dfs(0)


Fixed submission:
import sys
sys.setrecursionlimit(10**9)

s = input()
l = len(s)


def dfs(i):
   #    print("->", s[i:])
    if i == l:
        print("YES")
        exit()
    if s[i:i+5] == "dream":
        if i+6 < l and s[i+5:i+7] == "er":
            dfs(i+7)
        dfs(i+5)
    elif s[i:i+5] == "erase":
        if i+5 < l and s[i+5] == "r":
            dfs(i+6)
        dfs(i+5)


dfs(0)
print("NO")

Buggy python submission (verdict: Runtime Error):
s = input()

l = len(s)


def dfs(i):
    #    print("->", s[i:])
    if i == l:
        print("YES")
        exit()
    if s[i:i+5] == "dream":
        if i+7 < l and s[i+5:i+7] == "er":
            dfs(i+7)
        dfs(i+5)
    elif s[i:i+5] == "erase":
        if i+5 < l and s[i+5] == "r":
            dfs(i+6)
        dfs(i+5)


dfs(0)
print("NO")


Fixed submission:
import sys
sys.setrecursionlimit(10**9)

s = input()
l = len(s)


def dfs(i):
   #    print("->", s[i:])
    if i == l:
        print("YES")
        exit()
    if s[i:i+5] == "dream":
        if i+6 < l and s[i+5:i+7] == "er":
            dfs(i+7)
        dfs(i+5)
    elif s[i:i+5] == "erase":
        if i+5 < l and s[i+5] == "r":
            dfs(i+6)
        dfs(i+5)


dfs(0)
print("NO")

Buggy python submission (verdict: Runtime Error):
s = input()

l = len(s)


def dfs(i):
    if i == l:
        print("YES")
        exit()
    if s[i:i+5] == "dream":
        if i+7 < l and s[i+5:i+7] == "er":
            dfs(i+7)
        dfs(i+5)
    elif s[i:i+5] == "erase":
        if i+6 < l and s[i+5] == "r":
            dfs(i+6)
        dfs(i+5)


dfs(0)


Fixed submission:
import sys
sys.setrecursionlimit(10**9)

s = input()
l = len(s)


def dfs(i):
   #    print("->", s[i:])
    if i == l:
        print("YES")
        exit()
    if s[i:i+5] == "dream":
        if i+6 < l and s[i+5:i+7] == "er":
            dfs(i+7)
        dfs(i+5)
    elif s[i:i+5] == "erase":
        if i+5 < l and s[i+5] == "r":
            dfs(i+6)
        dfs(i+5)


dfs(0)
print("NO")

Buggy python submission (verdict: Runtime Error):
ans = "NO"
s = input()


def dfs(s):
    ret = 0
    if len(s) == 0:
        return 1

    if s[:5] == 'dream' or s[:5] == 'erase':
        ret += dfs(s[5:])
    if s[:7] == 'dreamer':
        ret += dfs(s[7:])
    if s[:6] == 'eraser':
        ret += dfs(s[6:])
    return ret


if dfs(s):
    ans = "YES"
print(ans)


Fixed submission:
import sys
sys.setrecursionlimit(10**9)

s = input()
l = len(s)


def dfs(i):
   #    print("->", s[i:])
    if i == l:
        print("YES")
        exit()
    if s[i:i+5] == "dream":
        if i+6 < l and s[i+5:i+7] == "er":
            dfs(i+7)
        dfs(i+5)
    elif s[i:i+5] == "erase":
        if i+5 < l and s[i+5] == "r":
            dfs(i+6)
        dfs(i+5)


dfs(0)
print("NO")