Why do you have an array, j, with 20 elements, when you only use the first element in the array? Why is the array given such a generic name?
I think that, in the future, I'll just call you person, since you ARE a person. No need to get fancy with meaningful names, person, when any old name will do.
You have an array of values, too. Two of them, actually. You only ever use the first value in each array.
What it appears that you want to do is increment the index into the array, NOT the value in the first position in array.