My 16-year old friend figured out how to do this. Here's the code he used:

{
ifstream fin("assign_07_in.txt");
if (!fin.is_open())
exit(1);

int RoadNS[70] = { 0 };
int RoadWE[70] = { 0 };

fin.ignore(100, '\n');
int temp_input;
int i = 0;
while (fin >> temp_input && temp_input != -999)
{
RoadNS[i] = temp_input;
i++;
}
fin.get();
i = 0;
fin.ignore(100, '\n');
while (fin >> temp_input && temp_input != -999)
{
RoadWE[i] = temp_input;
i++;
}
fin.close();
}