print "Match1\n" if "aa1" =~ /^(a)\1()1$/;;
Match1

print "Match1\n" if "aa1" =~ /^(a)\1(?:)1$/;;
Match1

print "Match1\n" if "aa1" =~ /^(a)\1(?:1)$/;;
Match1

print "Match1\n" if "aa1" =~ /^(a)\1+1$/;;
Match1

print "Match1\n" if "aa1" =~ /^(a)\1{1}1$/;;
Match1