Mario has 22 pieces of paper, some of which are square-shaped and the rest are triangular. He cuts 6 of the square pieces along one of their diagonals from vertex to vertex. Then he counts the total number of vertices of the 28 pieces of paper obtained and observes that there are 90 vertices. How many square pieces did he have before making the cuts?


A) 10
B) 11
C) 13
D) 12