Respuesta :

Crossing times:

Ricci 1 minute

Poccia 2 minutes

Bellonio 5 minutes

Zajac 10 minutes.

=============================  Crossings ==================

R+P ->    2 minutes

R <-         1 minute

B+Z -> 10 minutes

P <-      2 minutes

R+P -> 2 minutes

==================================================

Total 17 minutes