public class Matrix {
    public static void main(String[] args) {
        try{
            BufferedReader rd = new BufferedReader(new InputStreamReader(System.in));
            int n = Integer.parseInt(rd.readLine());
            ...
            swapStrings(a,100000,2);
        }
        catch(NumberFormatException e){
            System.out.println("n - is not int! Exit");
        }
    catch (IllegalArgumentException illegalEx) {
        System.out.println(illegalEx.getMessage());
    }
    }


    static void swap(int[][] a, int first, int second){
        if(first < second && second < a.length){
            ...
            }
        }
        else{
            throw new IllegalArgumentException("Error while swapping - incorrect input values!");
        }
    }
}