Problem 1. Five boys are weighed in pairs in all possible combinations. The scale showed the following weights: $72 \mathrm{~kg}, 75 \mathrm{~kg}, 76 \mathrm{~kg}, 77 \mathrm{~kg}, 78$ $\mathrm{kg}, 80 \mathrm{~kg}, 81 \mathrm{~kg}, 82 \mathrm{~kg}, 85 \mathrm{~kg}$ and $86 \mathrm{~kg}$. What is the total weight of all five boys?