Editorial

A triangle is equilateral if all its sides are equal. If it is not equilateral, check if it is isosceles – this requires two sides to be equal. If the triangle is neither equilateral nor isosceles, then it is scalene.

Algorithm realization

Read the input data.

scanf("%d %d %d",&a,&b,&c);

Check if the triangle is equilateral.

if ((a == b) && (b == c))
  puts("1");
else

Check if the triangle is isosceles.

if ((a == b ) || (a == c) || (b == c))
  puts("2");
else

Otherwise, the triangle is scalene.

  puts("3");

Java realization

import java.util.*;

public class Main
{
  public static void main(String[] args)
  {
    Scanner con = new Scanner(System.in);
    int a = con.nextInt();
    int b = con.nextInt();
    int c = con.nextInt();
    
    if ((a == b) && (b == c))
      System.out.println("1");
    else 
    if ((a == b ) || (a == c) || (b == c))
      System.out.println("2");
    else
      System.out.println("3");
    
    con.close();
  }
}

Python realization

Read the input data.

a, b, c = map(int, input().split())

Check if the triangle is equilateral.

if a == b and b == c:
  print("1")
else:

Check if the triangle is isosceles.

  if a == b or a == c or b == c:
    print("2")
  else:

Otherwise, the triangle is scalene.

    print("3")