Rodney models the factorization of a trinomial with algebra tiles as shown. An algebra tile configuration. 4 tiles are in the Factor 1 spot: 1 is labeled + x, 3 are labeled +. 4 tiles are in the Factor 2 spot: 1 is labeled + x and 4 are labeled negative. 14 tiles are in the Product spot: 1 is labeled + x squared and below it is a tile labeled negative x. To the right of negative x in 3 columns and 4 rows are 12 tiles labeled negative.

Rodney forgot to place x-tiles in zero pairs in the model of the trinomial. How many zero pairs of x-tiles should he place in the model?