Level1Index in TOC report

Hi Community, 

Did anyone try level1Index in TOC report ? By default there is a variable called "level2Index" to display level-2 but there is no a variable to display level-1 index. 

The out of the box expression for level2Index is $F{level} == 1 ? 0 : ($F{level} == 2 ? ($V{level2Index} + 1) : $V{level2Index})

Tried creating level1Index as similar to above one as $F{level} == 0 ? 0 : ($F{level} == 1 ? ($V{level1Index} + 1) : $V{level1Index}) but it doesn't work and thrown null value.

In other words, from below I need the bold ones in level1 index in TOC. 

{

1. leve1

         1. level2

          2. level2

2. level1

        1.level2

        2.level2

}

Any help would appricated on this. 

Thank you in advance. 

Sadakar Pochampalli