#  Here are a variety of different solutions to the find(s,c)
#   problem by various students and one teacher...

############ CYRUS CURSETJEE:
def cfind(s,c):  # Cyrus
    if s[0] == c[-1]:
        return len(c) - 1
    if len(s) == 1:
        return -1
    return cfind(s[1:],s[0]+c)

############# Ivan Wei
def ifind(s, c):  # Ivan
    if not s:
        return -1
    if s[0] == c:
        return 0
    result = ifind(s[1:], c)
    if result == -1:
        return -1
    return 1 + result

######### Deven Maheshwari + Maxwell Zen	
def find(s,c):  #Deven + Maxwell
    try:
        if s[0] == c:
            return 0
        else:
            if find(s[1:],c) == -1:
                return -1
            return find(s[1:],c)+1
    except:
        return -1

############ Gregory Wickham
def gfind(s,c):  # Gregory
    if s == '':
        return -1
    if s[-1] == c:
        return len(s)-1
    return gfind(s[:-1],c)

############ Mr. Brooks	
def pbfind_helper(s,c,n):  # Mr. Brooks
    if s == '':
        return -1
    if s[0] == c:
        return n
    return pbfind_helper(s[1:],c,n+1)

def pbfind(s,c):
    return pbfind_helper(s,c,0)

############# A different version of Reverse(L), reversing 2 elements
#   each time...  Alvin Li
def ireverse(L):  # Alvin
    if len(L) <= 1:
        return L
    return [L[-1]] + ireverse(L[1:-1]) + [L[0]]