var stack1 = [];
var stack2 = [];
function push(node)
{
    if(stack2.length === 0 && stack1.length === 0){
        stack1.push(node);
        stack2.push(node);
    } else{
        stack1.push(node);
        var stack2Top = stack2[stack2.length-1];
        if(node < stack2Top)
            stack2.push(node)
        else
            stack2.push(stack2Top);
    }
}
function pop()
{
    stack2.pop();
    return stack1.pop();
}
function top()
{
    return stack1[stack1.length-1];
}
function min()
{
  return stack2[stack2.length-1];
}