import java.lang.RuntimeException;

class Pino1 {

    private int[] array;
    private int top;

    public Pino1() {
        this.array = new int[100];
        this.top = 0;
    }

    public Pino1(int eka) {
        this.array = new int[100];
        this.top = 0;
        this.array[top++] = eka;
    }

    public int pop() {
        if ( this.isEmpty() )
            throw new RuntimeException();
        int elem = this.array[--this.top];
        /* Varmistetaan, että pinossa on korkeintaan 100 vapaata paikkaa. */
        if (this.top < this.array.length - 100 ) {
            int[] temp = new int[this.array.length - 100];
            System.arraycopy(this.array, 0, temp, 0, this.top);
            this.array = temp;
        }
        return elem;
    }

    public void push(int elem) {
        if ( this.top == this.array.length ) {
            int[] temp = new int[this.top + 100];
            System.arraycopy(this.array, 0, temp, 0, this.top);
            this.array = temp;
        }
        this.array[this.top++] = elem;
    }

    public boolean isEmpty() {
        if ( this.top == 0 ) return true;
        else return false;
    }
}