#include <bits/stdc++.h>
using namespace std;

void ravno(vector<vector<int>> &a, vector<vector<int>> &b)
{
    for (int i = 0; i < 4; i++)
    {
        for (int j = 0; j < 4; j++)
        {
            a[i][j] = b[i][j];
        }
    }
}


int main()
{
    int n = 16;
    vector<vector<int>> field(4, vector<int>(4, 0));
    for (int i = 0; i < 4; i++)
    {
        for (int j = 0; j < 4; j++)
        {
            cin >> field[i][j];
            if (field[i][j] == 'W')
                field[i][j] = 0;
            else
                field[i][j] = 1;
        }
    }
    vector<vector<int>> mas(3, vector<int>(3));
    for (int i = 0; i < 3; i++)
    {
        for (int j = 0; j < 3; j++)
        {
            cin >> mas[i][j];
        }
    }
    int mn = 17;
    vector<vector<int>> wb;
    ravno(wb, field);
    for (int mask = 0; mask < (1 << n); mask++)
    {
        int k = 0;
        for (int j = 0; j < n; j++)
        {
            if (mask & (1 << j))
            {
                k++;
                int xx = mask / 4;
                int yy = mask % 4;
                for (int x = xx - 1; x <= xx + 1; x++)
                {
                    for (int y = yy - 1; y <= yy + 1; y++)
                    {
                        if (x >= 0 && x < 4 && y >= 0 && y < 4)
                        {
                            if (mas[x - xx + 1][y - yy + 1] == 1)
                            {
                                wb[x][y] = (wb[x][y] + 1) & 2;
                            }
                        }
                    }
                }
            }
        }
        int sum = 0;
        for (int x = 0; x < 4; x++)
        {
            for (int y = 0; y < 4; y++)
            {
                sum += wb[x][y];
            }
        }
        if (sum == 0 || sum == 16)
        {
            mn = min(mn, k);
        }
        ravno(wb, field);
    }
    if (mn == 17)
        cout << "Impossible";
    else
        cout << mn;
}