Java coding for Nested IF

import java.io.*;
class Grading
{
public static void main(String args[])throws java.io.IOException
{
BufferedReader stdin=new BufferedReader(new InputStreamReader(System.in));

System.out.println("Enter the no one:");
int no1=Integer.parseInt(stdin.readLine());
BufferedReader stdin1=new BufferedReader(new InputStreamReader(System.in));
System.out.println("Enter the no two:");
int no2=Integer.parseInt(stdin1.readLine());
BufferedReader stdin2=new BufferedReader(new InputStreamReader(System.in));
System.out.println("Enter the no three:");
int no3=Integer.parseInt(stdin2.readLine());

float avg;
avg=(no1+no2+no3)/3;
String grade;

if (avg>=70 && 100>=avg)
{
grade="A";
}
else if (70>avg && avg>=55)
{
grade="B";
}
else if (55>avg && avg>=40)
{
grade="C";
}
else if (avg<40) grade="F";
}
else
{
grade="error";
}
System.out.println("the average is:"+avg);
System.out.println("the grade is:"+grade);
}
}