#include "subroutines.h"

int subroutine_3(string fname_1, string fname_2, int n)
{
    double *vector = new double[n];
    if (vector == NULL) {
        free(vector);
        return -1;
    }

    fstream fp(fname_1, fstream::in);
    if (!fp.is_open()) {
        free(vector);
        return 1;
    }

    for (int i = 0; i < n; i++)
        fp >> vector[i];
    fp.close();

    fp.open(fname_2, fstream::out);
    if (!fp.is_open()) {
        free(vector);
        return 2;
    }

    double result = 1;
    for (int i = 0; i < n; i++)
        result *= vector[i];
    result = sqrt(abs(result));

    fp << std::fixed;
    fp << setw(9) << setprecision(3) << result;
    fp.close();

    return 0;
}