5 pearls are connected in a string as shown in the figure. Each pearl has a written natural number. You are allowed to add up numbers of the pearls which are directly next to each other. You can use a number of a pearl, add up 2 numbers, … add up 5 numbers, if the pearls are next to each other.

Now assign 5 numbers to 5 pearls so that you can make all the 21 numbers, 1, 2, …, 21.