package Fresherpractice;

public class c {

public static void main(String[] args)  {

int sum=0;

for(int i=1; (i>=1)&&(i<=100);i++) {

if(i%3!=0) {

sum+=i;

                     }

                                                                             }

 System.out.println(sum);

}

}

Error: Main method not found in class Fresherpractice.c, please define the main method as:

   public static void main(String[] args)

or a JavaFX application class must extend javafx.application.Application