package stackProblems2;

public class TwoStacks {
	
	int a[];
	int top1, top2;
	
	public TwoStacks(int capacity) {
		a = new int[capacity];
		top1 = -1;
		top2 = capacity;
	}
	
	void push1(int data) throws Exception {
		if(top1+1<top2) { // overflow check
			top1++;
			a[top1] = data;
		} else {
			throw new Exception("Stack array is Full");
		}
	}
	
	void push2(int data) throws Exception {
		if(top1+1<top2) {
			top2--;
			a[top2] = data;
		} else {
			throw new Exception("Stack array is Full");
		}
	}
	
	int pop1() throws Exception  {
		if(top1 > -1) { //underflow check
			int res = a[top1];
			top1--;
			return res;
		} else {
			throw new Exception("Stack1 is Empty");
		}
	}
	
	int pop2() throws Exception  {
		if(top2 < a.length) {
			int res = a[top2];
			top2++;
			return res;
		} else {
			throw new Exception("Stack2 is Empty");
		}
	}

}