The weight of seven boys B1, B2, B3, B4, B5, B6 and B7 are compared. The weight of no two boys is the same. The weight of B4 is less than only three boys. The weight of B1 is more than B7. The weight of B2 is the most. B5 and B6 both weigh more than B1. The weight of B3 is less than that of B7.
How many boys weigh less than B1?
1
4
2
3
3
1
4
2