x=raw_input('Введите строку: ')
i=0
j=1
while j<=len(x):
    if type(x[i])==type(x[i+1]):
        a=x[i]*int(x[i+1])
        print a,
        i+=1      
    j+=1

>>> import re
>>> sa = 'Z15x3A12'
>>> sb = ''.join([c * int(n) for c, n in zip(re.findall('[^\d]+', sa), re.findall('\d+', sa))])
>>> sb
'ZZZZZZZZZZZZZZZxxxAAAAAAAAAAAA'
>>>

sb = ''.join(c * int(n) for c, n in re.findall( r'([^\d]+)(\d+)', sa))

''.join(m[0]*int(m[1:]) for m in re.findall('.\d+', sa))

eval(re.sub('(.)(\d+)', r'"\1"*\2+', sa)[:-1])

re.sub('(.)(\d+)', lambda x: x.groups()[0]*int(x.groups()[1]), sa)

re.sub('.\d+', lambda x: x.group()[0]*int(x.group()[1:]), sa)

x="Z15x3A2"
i=0
j=1
while j<=len(x):
    if type(x[i])==str:
        print 'strrrrrr',
        i+=1
    else:
        print 'intttt',
        i+=1
    j+=1

x="Z15x3A2"
i=0
while i<len(x):
    try:
        if int(x[i]):
            print 'int'
    except: 
        print 'str'
    i += 1