std::cin.getline() space and new line setting input

[Lang]

Hey there.

What I'm trying to accomplish is simply. A user enters the input '2 1 3 18' (not including the quotes)
and all 4 numbers are put into an array.

This is my code thus far (note variables are set up properly etc the only issue I'm having is saving the input)

for (int i = 0; i < m; ++i){
   counter = 0;

   while (counter < n){
       cin.getline(input, 100, ' \n'); //so either a space or a new line is like pressing enter
       aMatrix[i][counter] = (int)input; //I wanted to put (long double)input; but that doesn't work - any ideas?
       counter++;
   }
}

Also running the code line for line, the first time cin.getline() is run I'm unable to enter anything.

Thanks in advance!