class Solution {
    public List<String> buildArray(int[] target, int n) {
        ArrayList<String> stack=new ArrayList<String>();
        int x=0;
        for(int i=1;i<=n && x<target.length; i++){
            stack.add("Push");
            if(target[x]==i) x++;
            else stack.add("Pop");
        }
        
        return stack;
    }
}