#!/usr/bin/env python
def getfile():
    file=raw_input('enter your filename:')
    if file=="":
        print 'no input,again'
        return getfile()
    else:
        try:
            f=open(file,'r')
        except IOError,e:
            print 'open file error:',e
            return getfile()
        else:
            return f

def getlinenum():
    num=0
    for line in files:
        num+=1
    return num

while True:
    files=getfile()
    lines=getlinenum()
    print 'line is %d'%lines