data – Select elements of a list

Suppose we have the following data list

data = {{-1, 2}, {0, 3}, {6, 6}, {1}, {-5, 1}, {0, 0}, {3}, {-3, 3}, {1, 2}, {1}, 
        {0, -1}, {2, 2}, {7}, {5, 5}, {2, 2}, {3, -3}, {4, -4}, {2, -2}, {7}}

The data are formatted as follows: first, we have N rows of (a,b) elements and then a row with a single element c which determines the end and the class of the (a,b) sub-list.
My question: how can I choose all the (a,b) elements for a given value of c?

For example, in the above list choose all elements for which c = 1 and create data2 as

data2 = {{-1, 2}, {0, 3}, {6, 6}, {-3, 3}, {1, 2}}