Buggy python submission (verdict: Runtime Error):
import sys

tree={}
np = -1

home=0
tree[home]=[None, None, None]

def search(p, x):
    node_pos=[None,None]
    while p != None:
        tmp = tree[p]
        if tmp[0] == x:
            node_pos[0] = p
            return node_pos
        node_pos[1] = p
        if x < tmp[0]:
            p = tmp[1]
        else:
            p = tmp[2]
    return node_pos

def node(x):
    global np
    np += 1
    tree[np] = [x, None, None]
    return np

def insert(p, x):
    if p == None or np == -1: return node(x)
    tmp = tree[p]
    if x== tmp[0]: return p
    elif x<tmp[0]:
        tree[p][1]=insert(tmp[1],x)
    else:
        tree[p][2]=insert(tmp[2],x)
    return p

def deletenode(p, parent, child=None):
        if tree[parent][1]==p:
            tree[parent][1] = child
        elif tree[parent][2]==p:
            tree[parent][2] = child
        del tree[p]

def searchmin(p):
    if tree[p][1]!=none:
        p = tree[p][1]
    return p

def delete(x):
    p, parent = search(0,x)
    if tree[p][1:3]==[None,None]:
        deletenode(p,parent)
    elif tree[p][1]==None:
        deletenode(p, parent, tree[p][2])
    elif tree[p][2]==None:
        deletenode(p, parent, tree[p][1])
    else:
        p1=searchmin(tree[p][2])
        if tree[parent][1]==p:
            tree[parent][1] = p1
        elif tree[parent][2]==p:
            tree[parent][2] = p1
        tree[p1][1]=tree[p][1]
        tree[p1][2]=tree[p][2]
        del tree[p]
    return

def preorder(p):
    if p == None: return []
    p1, p2 = tree[p][1:3]
    return [tree[p][0]] + preorder(p1) + preorder(p2)

def inorder(p):
    if p == None: return []
    p1, p2 = tree[p][1:3]
    return inorder(p1) + [tree[p][0]] +inorder(p2)

n = int(input())
i = 0
while i<n:
    s = raw_input()
    if s[0]=='i':
        insert(0,int(s[7:]))
    elif s[0]=='f':
        if search(0,int(s[5:]))[0]!=None: print 'yes'
        else print 'no'
    elif s[0]=='d':
        delete(0,int(s[7:]))
    elif s[0]=='p':
        print ' ' + ' '.join(map(str, inorder(home)))
        print ' ' + ' '.join(map(str, preorder(home)))
    i += 1

Fixed submission:
import sys

tree={}
np = -1

home=0
tree[home]=[None, None, None]

def search(p, x):
    node_pos=[None,None]
    while p != None:
        tmp = tree[p]
        if tmp[0] == x:
            node_pos[0] = p
            return node_pos
        node_pos[1] = p
        if x < tmp[0]:
            p = tmp[1]
        else:
            p = tmp[2]
    return node_pos

def node(x):
    global np
    np += 1
    tree[np] = [x, None, None]
    return np

def insert(p, x):
    if p == None or np == -1: return node(x)
    tmp = tree[p]
    if x== tmp[0]: return p
    elif x<tmp[0]:
        tree[p][1]=insert(tmp[1],x)
    else:
        tree[p][2]=insert(tmp[2],x)
    return p

def deletenode(p, parent, child=None):
        if tree[parent][1]==p:
            tree[parent][1] = child
        elif tree[parent][2]==p:
            tree[parent][2] = child
        del tree[p]

def searchmin(p):
    while tree[p][1]!=None:
        p = tree[p][1]
    return p

def delete(x):
    p, parent = search(0,x)
    if tree[p][1:3]==[None,None]:
        deletenode(p,parent)
    elif tree[p][1]==None:
        deletenode(p, parent, tree[p][2])
    elif tree[p][2]==None:
        deletenode(p, parent, tree[p][1])
    else:
        p1=searchmin(tree[p][2])
        p1, parent1 = search(0,tree[p1][0])

        if tree[parent1][1]==p1:
            tree[parent1][1] = None
        elif tree[parent1][2]==p1:
            tree[parent1][2] = None

        if tree[parent][1]==p:
            tree[parent][1] = p1
        elif tree[parent][2]==p:
            tree[parent][2] = p1
        tree[p1][1]=tree[p][1]
        tree[p1][2]=tree[p][2]
        del tree[p]
    return

def preorder(p):
    if p == None: return []
    p1, p2 = tree[p][1:3]
    return [tree[p][0]] + preorder(p1) + preorder(p2)

def inorder(p):
    if p == None: return []
    p1, p2 = tree[p][1:3]
    return inorder(p1) + [tree[p][0]] +inorder(p2)

n = int(input())
i = 0
while i<n:
    s = raw_input()
    if s[0]=='i':
        p = insert(0,int(s[7:]))
    elif s[0]=='f':
        if search(0,int(s[5:]))[0]!=None: print 'yes'
        else: print 'no'
    elif s[0]=='d':
        delete(int(s[7:]))
    elif s[0]=='p':
        print ' ' + ' '.join(map(str, inorder(home)))
        print ' ' + ' '.join(map(str, preorder(home)))
    i += 1

Buggy python submission (verdict: Runtime Error):
import sys

tree={}
np = -1

home=0
tree[home]=[None, None, None]

def search(p, x):
    node_pos=[None,None]
    while p != None:
        tmp = tree[p]
        if tmp[0] == x:
            node_pos[0] = p
            return node_pos
        node_pos[1] = p
        if x < tmp[0]:
            p = tmp[1]
        else:
            p = tmp[2]
    return node_pos

def node(x):
    global np
    np += 1
    tree[np] = [x, None, None]
    return np

def insert(p, x):
    if p == None or np == -1: return node(x)
    tmp = tree[p]
    if x== tmp[0]: return p
    elif x<tmp[0]:
        tree[p][1]=insert(tmp[1],x)
    else:
        tree[p][2]=insert(tmp[2],x)
    return p

def deletenode(p, parent, child=None):
        if tree[parent][1]==p:
            tree[parent][1] = child
        elif tree[parent][2]==p:
            tree[parent][2] = child
        del tree[p]

def searchmin(p):
    if tree[p][1]!=none:
        p = tree[p][1]
    return p

def delete(x):
    p, parent = search(0,x)
    if tree[p][1:3]==[None,None]:
        deletenode(p,parent)
    elif tree[p][1]==None:
        deletenode(p, parent, tree[p][2])
    elif tree[p][2]==None:
        deletenode(p, parent, tree[p][1])
    else:
        p1=searchmin(tree[p][2])
        if tree[parent][1]==p:
            tree[parent][1] = p1
        elif tree[parent][2]==p:
            tree[parent][2] = p1
        tree[p1][1]=tree[p][1]
        tree[p1][2]=tree[p][2]
        del tree[p]
    return

def preorder(p):
    if p == None: return []
    p1, p2 = tree[p][1:3]
    return [tree[p][0]] + preorder(p1) + preorder(p2)

def inorder(p):
    if p == None: return []
    p1, p2 = tree[p][1:3]
    return inorder(p1) + [tree[p][0]] +inorder(p2)

n = int(input())
i = 0
while i<n:
    s = raw_input()
    if s[0]=='i':
        insert(0,int(s[7:]))
    elif s[0]=='f':
        if search(0,int(s[5:]))[0]!=None: print 'yes'
        else: print 'no'
    elif s[0]=='d':
        delete(int(s[7:]))
    elif s[0]=='p':
        print ' ' + ' '.join(map(str, inorder(home)))
        print ' ' + ' '.join(map(str, preorder(home)))
    i += 1

Fixed submission:
import sys

tree={}
np = -1

home=0
tree[home]=[None, None, None]

def search(p, x):
    node_pos=[None,None]
    while p != None:
        tmp = tree[p]
        if tmp[0] == x:
            node_pos[0] = p
            return node_pos
        node_pos[1] = p
        if x < tmp[0]:
            p = tmp[1]
        else:
            p = tmp[2]
    return node_pos

def node(x):
    global np
    np += 1
    tree[np] = [x, None, None]
    return np

def insert(p, x):
    if p == None or np == -1: return node(x)
    tmp = tree[p]
    if x== tmp[0]: return p
    elif x<tmp[0]:
        tree[p][1]=insert(tmp[1],x)
    else:
        tree[p][2]=insert(tmp[2],x)
    return p

def deletenode(p, parent, child=None):
        if tree[parent][1]==p:
            tree[parent][1] = child
        elif tree[parent][2]==p:
            tree[parent][2] = child
        del tree[p]

def searchmin(p):
    while tree[p][1]!=None:
        p = tree[p][1]
    return p

def delete(x):
    p, parent = search(0,x)
    if tree[p][1:3]==[None,None]:
        deletenode(p,parent)
    elif tree[p][1]==None:
        deletenode(p, parent, tree[p][2])
    elif tree[p][2]==None:
        deletenode(p, parent, tree[p][1])
    else:
        p1=searchmin(tree[p][2])
        p1, parent1 = search(0,tree[p1][0])

        if tree[parent1][1]==p1:
            tree[parent1][1] = None
        elif tree[parent1][2]==p1:
            tree[parent1][2] = None

        if tree[parent][1]==p:
            tree[parent][1] = p1
        elif tree[parent][2]==p:
            tree[parent][2] = p1
        tree[p1][1]=tree[p][1]
        tree[p1][2]=tree[p][2]
        del tree[p]
    return

def preorder(p):
    if p == None: return []
    p1, p2 = tree[p][1:3]
    return [tree[p][0]] + preorder(p1) + preorder(p2)

def inorder(p):
    if p == None: return []
    p1, p2 = tree[p][1:3]
    return inorder(p1) + [tree[p][0]] +inorder(p2)

n = int(input())
i = 0
while i<n:
    s = raw_input()
    if s[0]=='i':
        p = insert(0,int(s[7:]))
    elif s[0]=='f':
        if search(0,int(s[5:]))[0]!=None: print 'yes'
        else: print 'no'
    elif s[0]=='d':
        delete(int(s[7:]))
    elif s[0]=='p':
        print ' ' + ' '.join(map(str, inorder(home)))
        print ' ' + ' '.join(map(str, preorder(home)))
    i += 1