Exercise_1.java

class Stack { 
    //Please read sample.java file before starting.
  //Kindly include Time and Space complexity at top of each file
    static final int MAX = 1000; 
    int top; 
    int a[] = new int[MAX]; // Maximum size of Stack 
  
    boolean isEmpty() 
    { 
        if(top<0) return true;
        else return false;//Write your code here 
    } 

    Stack() 
    { 
       top=-1; //Initialize your constructor 
    } 
  
    boolean push(int x) 
    { 
       if(top>= MAX-1) return false;
       else{
        top++;
        a[top]=x;
        return true;
       } //Check for stack Overflow
        //Write your code here
    } 
  
    int pop() 
    { 
        if(top<0)
            {
                System.out.println("Stack Underflow");
                return 0;}
                
             else{
                int res=a[top];
                top--;
                return res;
             }   //If empty return 0 and print " Stack Underflow"
        //Write your code here
    } 
  
    int peek() 
    { 
        if(top<0) return 0;
        return a[top];//Write your code here
    } 
} 
  
// Driver code 
class Main { 
    public static void main(String args[]) 
    { 
        Stack s = new Stack(); 
        s.push(10); 
        s.push(20); 
        s.push(30); 
        System.out.println(s.pop() + " Popped from stack"); 
    } 
}