game based on the Goldbach's conjecture

Please allow us to introduce you an original game of quick thinking. The idea is simple: fill a jerrycan. But the method is complex. The amounts you can use will be given. You can always do with 2 or 3 attempts, but if you take a chance and you exceed the maximum weight the result is negative, the same way that if you spend time.

Based on Goldbach's conjecture: Every integer greater than 5 can be expressed as the sum of two primes if the number is even or as the sum of three primes if the number is odd.

You must fill the jerrycan before countdowns comes to an end. The fewer numbers need, more points and you accumulate the remaining time.