why output is wrong ?
package pl.codegym.task.task19.task1908;
/*
Wybieranie numerów
*/
import java.io.FileReader;
import java.io.FileWriter;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.FileReader;
import java.io.InputStreamReader;
public class Solution {
public static void main(String[] args) throws Exception {
BufferedReader readera = new BufferedReader(new InputStreamReader(System.in));
String nazwa1 = readera.readLine();
String nazwa2 = readera.readLine();
readera.close();
FileReader readerv = new FileReader(nazwa1);
BufferedReader reader = new BufferedReader(readerv);
FileWriter writerv = new FileWriter(nazwa2);
BufferedWriter writer = new BufferedWriter(writerv);
String a = "";
while(readerv.ready()){
int data = readerv.read();
if(data == ' '){
try{
int nom = Integer.parseInt(a);
writer.write(a);
a= "";
}
catch(Exception e){
}
}
else{
char c = (char) data;
a += c;
}
}
readerv.close();
writer.close();
reader.close();
writerv.close();
}
}