import java.util.Stack;

public class GetMinStack {

private Stack<Integer> stackData;

private Stack<Integer> stackMin;

public GetMinStack() {

this.stackData = new Stack<Integer>();

this.stackMin = new Stack<Integer>();

}

public void push(int obj) {

this.stackData.push(obj);

if (this.stackMin.isEmpty()) {

this.stackMin.push(obj);

} else {

int minnum = Math.min(obj, this.stackMin.peek());

this.stackMin.push(minnum);

}

}

public Integer pop() {

if (this.stackData.isEmpty()) {

throw new RuntimeException("Your Stack is empty!");

}

int value = this.stackData.pop();

this.stackMin.pop();

return value;

}

public Integer getMin() {

if (this.stackMin.isEmpty()) {

throw new RuntimeException("Your stack is empty!");

}

return this.stackMin.peek();

}

public static void main(String[] args) {

GetMinStack mystack = new GetMinStack();

mystack.push(6);

System.out.println("Min: " + mystack.getMin());

mystack.push(7);

System.out.println("Min: " + mystack.getMin());

mystack.push(4);

System.out.println("Min: " + mystack.getMin());

mystack.push(2);

System.out.println("Min: " + mystack.getMin());

System.out.println("pop: " + mystack.pop());

System.out.println("Min: " + mystack.getMin());

System.out.println("pop: " + mystack.pop());

System.out.println("Min: " + mystack.getMin());

}

}