# To support positive/negative integer/float numbers, you could use a slightly modified regexp from http://stackoverflow.com/questions/385558/python-and-regex-question-extract-float-double-value:
 
import sys
def main():
    import re
 
    re_float = re.compile("""(?x)
       ^
          [+-]?\ *      # first, match an optional sign *and space*
          (             # then match integers or f.p. mantissas:
              \d+       # start out with a ...
              (
                  \.\d* # mantissa of the form a.b or a.
              )?        # ? takes care of integers of the form a
             |\.\d+     # mantissa of the form .b
          )
          ([eE][+-]?\d+)?  # finally, optionally match an exponent
       """)
 
    def extract_number(s, default=None):
        m = re_float.match(s)
        if not m:
            return default # no number found
        f = float(m.group(0)) 
        return  int(f) if f.is_integer() else f
 
### Example
 
    for s in sys.stdin:
        print(extract_number(s, default=0))
 
main()        
 

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

MTIzNGFscGhhCmExMjM0YXNkZgoxMjM0LjU2eXQKLTFlMjAuCjEyLjM0LjU2

1234alpha
a1234asdf
1234.56yt
-1e20.
12.34.56