#include <iostream>
#include <fstream>
#include <cmath>

using namespace std;

const int kdim = 20;

void gauss(int kdim1, int n, double a[kdim][kdim], double b[], double x[])
{
	double eps = 1.e-8;
	for(int k=0;k<n-1;k++)
	{
		if(fabs(a[k][k]<eps))
		{
			cout<<"Divide by Zero"<<endl;
			break;
		}
		for(int i=k+1;i<n;i++)
		{
			double factor = a[i][k]/a[k][k];
			for(int j=k+1;j<n;j++)
				a[i][j] -= factor*a[k][j];
			b[i] -= factor*b[k];
		}
	}
	x[n-1] = b[n-1]/a[n-1][n-1];
	for(int i=n-2;i>=0;i--)
	{
		double sum = 0.e0;
		for(int j=i+1;j<n;j++)
			sum += a[i][j]*x[j];
		x[i]=(b[i]-sum)/a[i][i];
	}
}

int main()
{
	double a[kdim][kdim];
	double b[kdim];
	double x[kdim];
	
	int n;

	ifstream in("matrix.dat");
	in>>n;
	for(int i=0;i<n;i++)
	{
		for(int j=0;j<n;j++)
			in>>a[i][j];
		in>>b[i];
	}
	in.close();
	gauss(kdim,n,a,b,x);
	ofstream out("solution.dat");
	for(int i=0;i<n;i++)
	{
		out<<i<<"  "<<x[i]<<endl;
	}
	out.close();
}