square.cpp

#include<fstream>

using namespace std;

int main(int argc, char* argv[])
{
    string input_file_path(argv[1]);
    string output_file_path("b.dat");
    ifstream f_in(input_file_path);
    int x;
    f_in >> x;
    ofstream f_out(output_file_path);
    f_out << x*x;
    return 0;
}