Язык: Java

import java.util.Scanner;

public class Triangle {

   public static void main(String args[]) {

     int a, b, c;

     Scanner input = new Scanner(System.in);

     System.out.println("Write the side \"a\": ");

     a = input.nextInt();

     System.out.println("\nWrite the side \"b\": ");

     b = input.nextInt();

     System.out.println("\nWrite the side \"c\": ");

     c = input.nextInt();

     if(a+b > c && b+c > a && a+c > b) {

         System.out.println("\nA triangle with sides: " + a + "; " + b + "; " +  c + " exists!");

     }

     else {

         System.out.println("\nA triangle with sides: " + a + "; " + b + "; " +  c + " doesnt exist!");

     }

     if(a==b && b==c && a==c) {

         System.out.println("\nAnd also, this triangle is equilateral!");

     }

     else if(a==b || b==c || a==c) {

         System.out.println("\nAnd also, this triangle is isosceles!");

     }

     else {

         System.out.println("\nAnd also, this triangle is arbitrary!");

     }

   }

}