S = 1 + 1 + 2 + 3 + 5 + …….... To n

import java.util.*;
class sum_series
{
    public static void main(String args[])
    {
        int a=1,b=1,s=2,n,c;
        Scanner sc = new Scanner(System.in);
        System.out.println("Enter the value of n");
        n=sc.nextInt();
        for(int i=1;i<n;i++)
        {
        
         c=a+b;
         s=s+c;
         a=b;
         b=c;
         
        }
        System.out.println("SUM="+s);
      
       
    }
}