Paired Pumpkins I

Dracula has $3$ pumpkins, labeled $1-3$. He knows the mass of each pair of pumpkins is (in kgs) is $19, 21,$ and $28$. Let $w_1,w_2,$ and $w_3$ be the weights of the three pumpkins. If possible, find $w_1^2 + w_2^2 + w_3^2$. If this is impossible, enter $-1$.