def check_char(string):
	import re  
	regex = r'^[a-z]$|^([a-z]).*\1$'
	 
	if(re.search(regex, string)): 
		return "Valid" 
	else: 
		return "Invalid" 
def check_char(string):
    import re
    regex2 = r"^[a-z]$|^([a-z]).*1$"
   
    if re.search(regex2, string):
        return "Valid"
    else:
        return "Invalid"