import java.util.*;
import java.util.regex.*;
import java.lang.*;
import java.io.*;
class Ideone
{
{
String unescapedStr
= "Retrying for error: [[\"billing\",\\{u'non_field_errors': [u'Invalid payment email provided']}\"]]"; String pattern
= "Retrying for error:.*\\[u'([^']+)"; Pattern r = Pattern.compile(pattern);
Matcher m = r.matcher(unescapedStr);
if (m.find()) {
System.
out.
println(m.
group(1)); }
}
}
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