Is this computer science?
If so, then the function you would need for your code is this...
_____
if (someValue%2 != 0) {
value *= -1;
}
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//basically number%2 == 0 means even so "!" means false so "not even" meaning "odd."
Assuming you are doing an array list (given a set value) or a for-loop with an
int someValue = Integer.parseInt(args[i]); inside (not given a set value and not restricted)
Otherwise ignore me....lol