content: package salads;
  
  import java.io.FileReader;
  import java.io.FileWriter;
  import java.io.IOException;
  import java.math.BigInteger;
  import java.util.Scanner;
  
  public class Salads {
      private static long combination(int numeric, int elementCount){
          BigInteger first = BigInteger.valueOf(1);
          BigInteger second = BigInteger.valueOf(1);
          BigInteger third = BigInteger.valueOf(1);
  
          int difference = numeric - elementCount;
          for ( ; numeric > 0; first = first.multiply(BigInteger.valueOf((numeric--))));
          for ( ; elementCount > 0; second = second.multiply(BigInteger.valueOf((elementCount--))));
          for ( ; difference > 0; third = third.multiply(BigInteger.valueOf((difference--))));
  
          BigInteger finish = first.divide(second.multiply(third));
          return Long.valueOf(String.valueOf(finish));
      }
  
      public static void main(String[] args) throws IOException {
          FileReader file = new FileReader("input.txt");
          Scanner sc = new Scanner(file);
          int ingredientCount = sc.nextInt();
  
          long result = 0;
          if(ingredientCount > 1){
              for(int i = 2; i <= ingredientCount; i++){
                  int ingredientUsed = ingredientCount - i;
                  long combination = combination(ingredientCount, ingredientUsed);
                  result += combination;
              }
          }
  
          FileWriter out = new FileWriter("output.txt");
          out.write(String.valueOf(result));
          out.close();
      }
  }
  