#!python

def nudger(str):
    def foo(i):
        c = i.next()
        while True:
            nudge = yield c
            if nudge:
                c = i.next()
    n = foo(iter(str))
    n.next()
    return n
       
def char(s):
    c = s.next()
    if c in map(chr, range(97,123)) + map(chr, range(65, 91)):
        s.send(1)
        return c
    
def digit(s):
    c = s.next()
    if c in map(chr, range(48,58)):
        s.send(1)
        return c
    
s = nudger("ab1984    ")   

print char(s)
print digit(s)
print char(s)

def zeroormore(p,eat):
    def foo(s):
        while eat != None:
            v,eat = eat(p(s))
        return v
    return foo

def baseten(sofar):
    def foo(nextdigit):
        if nextdigit==None:
            return (sofar,None)
        else:
            now = sofar*10 + int(nextdigit)
            return (now, baseten(now))
    return foo
            
number = zeroormore(digit,baseten(0))            
print number(s)