Find the average and grade of a student

Write a programe to input three marks of a student and determine the average. Print a suitable grade if the average is between;
75-100 – A

60-74 – B

50-59 – C

0-49 – D

Print an error message if a negative number is entered or if the number is not with in the range from 0 to 100.

class Results {
 public static void main(String[] args) {
  int x = 35;
  int y = 24;
  int z = 12;
  int average=0;
 if (x > 100 | y > 100 | z > 100 | x < 0 | y < 0 | z <0 ) {
  System.out.println("The entered number is not with in the range from 0 to 100. Please enter a valid number.");
 } else {
  average = (x + y + z) / 3;
  System.out.println("Average : " + average);
 } 
 if (average>75){
  System.out.println("Grade : A");
}else if(average>60){
  System.out.println("Grade : B");
}else if(average>50){
  System.out.println("Grade : c");
}else if(average>0){
  System.out.println("Grade : D");
}
}
}