Read Input file into an 3-D array c++

I am solving MDPs by value iteration method ,For that I need to store the data in a 3-D array of size [S][A][S]. How can i store this in this 3-D array ? My Input file looks like this . In the image you can see the input file , Ignore the first 2 lines as they are equal to S =20 and A = 5 ,from the 3rd line in the image , you can see chunks of data of size =20 written repetitively , total words are 20*5*20 = 4000