How to show only interger that starts with zero, equal spacing, non repeating label on v-axis

[ruchi goel]

I am using google chart API. I have to display only integer that starts with zero, equal spacing, non repeating label on v-axis. I tried the following

vaxis = {
        gridlines: {
               count: -1
         },
         viewWindow: {
               min: 0
         },
         format: '#'
     }   

But i am geeting -1, 0 ,1 label on v-axis