Calculate students marks grade using Java

import java.io.*;
class ssvstud
{
public static void main(String arg[])
{
int s[]=new int[9];
int n,z=0,x=0,y=0,w=0;
s[0]=60;s[1]=70;s[2]=80;s[3]=72;s[4]=48;s[5]=55;s[6]=25;s[7]=90;s[8]=99;
n=9;
for(int i=0;i<n;i++)
{
  if(s[i]>=81 && s[i]<=100)
  z=z+1;
}
System.out.println("students in the range(81-100)is="+z);
for(int i=0;i<n;i++)
{
  if(s[i]>=61 && s[i]<=80)
  y=y+1;
}
System.out.println("students in the range(61-80)is="+y);
for(int i=0;i<n;i++)
{
  if(s[i]>=41 && s[i]<=60)
  x=x+1;
}
System.out.println("students in the range(41-60)is="+x);
for(int i=0;i<n;i++)
{
  if(s[i]>=0 && s[i]<=40)
  w=w+1;
}
System.out.println("students in the range(0-40)is="+w);
}
}