Make chocolate

We want make a package of goal/ target kilos of chocolate. We have small bars (1 kilo each) and big bars (5 kilos each). Return the number of small bars to use, assuming we always use big bars before small bars.

Param 1 : small bars 1 kg each, param 2 big bars 5 kg each and param 3 is goal in kgs
Return : how many small bars to use or -1 if it cant be done with given small and big bars.
Examples:
make_chocolate(4, 1, 9) -> 4
make_chocolate(4, 1, 10) -> -1
make_chocolate(4, 1, 7) -> 2
*/

// target function signature, dont change the signature
public int makeChocolate(int small, int big, int goal_target) {

}