#include <math.h>
#include <mpi.h>
#include <stdio.h>

#define N 3003


void* allocate_memory(int rank)
{
    MPI_Win win;
    MPI_Aint size;
    void* baseptr;

    if (!rank)
    {
        size = N * N * sizeof(double);
        MPI_Win_allocate_shared(size, sizeof(int), MPI_INFO_NULL,
                                MPI_COMM_WORLD, &baseptr, &win);
    }
    else
    {
        int disp_unit;
        MPI_Win_allocate_shared(0, sizeof(int), MPI_INFO_NULL,
                                MPI_COMM_WORLD, &baseptr, &win);
        MPI_Win_shared_query(win, 0, &size, &disp_unit, &baseptr);
    }

    return baseptr;
}

void read_input(int* n, double* arr)
{
    scanf("%d", n);
    int i;
    for (i = 0; i < *n; i++)
    {
        int j;
        for (j = 0; j <= *n; j++)
        {
            scanf("%lf", &arr[i * (*n + 1) + j]);
        }
    }
}


void swap(int n, double* arr, int a, int b)
{
    int i;
    for (i = 0; i <= n; i++)
    {
        double temp = arr[a * (n + 1) + i];
        arr[a * (n + 1) + i] = arr[b * (n + 1) + i];
        arr[b * (n + 1) + i] = temp;
    }
}


void usual(int n, double* arr, int rank, int ncount, double* answer)
{
    int i;
    for (i = 0; i < n; i++)
    {
        int best = -1;
        int max_val = 0;
        int j;
        for (j = i; j < n; j++)
        {
            if (fabsl(arr[j * (n + 1) + i]) > max_val)
            {
                max_val = fabsl(arr[j * (n + 1) + i]);
                best = j;
            }
        }

        swap(n, arr, i, best);

        for (j = i + 1; j < n; j++)
        {
            double coef = arr[j * (n + 1) + i] / arr[i * (n + 1) + i];
            int k;
            for (k = i; k <= n; k++)
            {
                arr[j * (n + 1) + k] -= arr[i * (n + 1) + k] * coef;
            }
        }
    }

    for (i = n - 1; i >= 0; i--)
    {
        answer[i] = arr[i * (n + 1) + n];
        int j;
        for (j = i + 1; j < n; j++)
        {
            answer[i] -= answer[j] * arr[i * (n + 1) + j];
        }
        answer[i] /= arr[i * (n + 1) + i];
    }
}


void paral(int n, double* arr, int rank, int ncount, double* answer)
{
    int i;
    for (i = 0; i < n; i++)
    {
        if (!rank)
        {
            int best = -1;
            int max_val = 0;
            int j;
            for (j = i; j < n; j++)
            {
                if (fabsl(arr[j * (n + 1) + i]) > max_val)
                {
                    max_val = fabsl(arr[j * (n + 1) + i]);
                    best = j;
                }
            }

            swap(n, arr, i, best);
        }
        MPI_Barrier(MPI_COMM_WORLD);

        int j;
        for (j = i + 1; j < n; j++)
        {
            if (rank == j % ncount)
            {
                double coef = arr[j * (n + 1) + i] / arr[i * (n + 1) + i];
                int k;
                for (k = i; k <= n; k++)
                {
                    arr[j * (n + 1) + k] -= arr[i * (n + 1) + k] * coef;
                }
            }
        }

        MPI_Barrier(MPI_COMM_WORLD);
    }

    if (!rank)
    {
        for (i = n - 1; i >= 0; i--)
        {
            answer[i] = arr[i * (n + 1) + n];
            int j;
            for (j = i + 1; j < n; j++)
            {
                answer[i] -= answer[j] * arr[i * (n + 1) + j];
            }
            answer[i] /= arr[i * (n + 1) + i];
        }
    }
}


int main()
{
    MPI_Init(NULL, NULL);

    int rank, ncount;
    MPI_Comm_rank(MPI_COMM_WORLD, &rank);
    MPI_Comm_size(MPI_COMM_WORLD, &ncount);

    double* arr = allocate_memory(rank);

    int n;
    if (!rank)
    {
        read_input(&n, arr);

        int i;
        for (i = 1; i < ncount; i++)
        {
            MPI_Send(&n, 1, MPI_INT, i, 0, MPI_COMM_WORLD);
        }
    }
    else
    {
        MPI_Status st;
        MPI_Recv(&n, 1, MPI_INT, 0, 0, MPI_COMM_WORLD, &st);
    }

    double answer[N];
    paral(n, arr, rank, ncount, answer);

    if (!rank)
    {
        int i;
        for (i = 0; i < n; i++)
        {
            printf("x%d = %.2lf\n", i, answer[i]);
        }
    }

    MPI_Finalize();
}