#include <cstdlib>
#include <cstdio>
#include <iostream>
#include <queue>
#include <cstring>
using namespace std;
char map[5][5];
bool vis[65540],flag;
struct NOTE
{
	int num,rod,last;
}tp;
void read()
{
	for(int i=0;i<=3;i++)
	    scanf("%s",&map[i]);
}
void pretreat()
{
	tp.rod=0;tp.last=0;tp.num=0;
	for(int i=0;i<=3;i++)
	    for(int j=0;j<=3;j++)
		   if(map[i][j]=='w') tp.num+=1<<(4*i+j);
	vis[tp.num]=1;
	//cout<<tp.num<<endl;
}
void bfs()
{
	queue<NOTE> q;
    q.push(tp);
	while(!q.empty())
	{
		NOTE tmp=q.front();
		q.pop();
		int nb=tmp.num,lt=tmp.last,rd=tmp.rod;
		if(rd>=16) return;
		for(int i=lt+1;i<=16;i++)
		{
			int dk=nb;
			dk=dk^(1<<(i-1));
			
			if(((i-1)%4)!=0) dk=dk^(1<<(i-2));
			if(((i+1)%4)!=1) dk=dk^(1<<(i));
			if(i-4>0) dk=dk^(1<<(i-5));
			if(i+4<=16) dk=dk^(1<<(i+3));
			
			//cout<<dk<<endl;system("pause");
			
			if(dk==65535||dk==0)
			{
				printf("%d",rd+1);
				flag=1;
				return;
			}
			if(vis[dk]!=1)
			{
				vis[dk]=1;
				NOTE pq;
				pq.num=dk;pq.last=i;pq.rod=rd+1;
				q.push(pq);
			}
		}
	}
}
int main()
{
	read();
	pretreat();
	if(tp.num==65535||tp.num==0)
	{
		printf("0");
		return 0;
	}
	bfs();
	if(flag!=1) printf("Impossible");
	system("pause");
	return 0;
}