#include<iostream>
using namespace std;
struct data{int mp[5][5];//1白棋,2黑棋,0空格
}d[5000];
int next[5000]={1,2};//下一步走黑棋还是白棋,1为白,2为黑
int step[5000];
bool hash[4000000];
int xx[4]={0,0,1,-1},yy[4]={1,-1,0,0};
int t=0,w=2,flag=0;
bool equ(int a1,int a2,int a3,int a4){if(a1!=a2||a2!=a3||a3!=a4||a4!=a1)return 0;return 1;}
bool check(){for(int i=1;i<=4;i++){if(equ(d[w].mp[i][1],d[w].mp[i][2],d[w].mp[i][3],d[w].mp[i][4]))return 1;if(equ(d[w].mp[1][i],d[w].mp[2][i],d[w].mp[3][i],d[w].mp[4][i]))return 1;}if(equ(d[w].mp[1][1],d[w].mp[2][2],d[w].mp[3][3],d[w].mp[4][4]))return 1;if(equ(d[w].mp[1][4],d[w].mp[2][3],d[w].mp[3][2],d[w].mp[4][1]))return 1;return 0;
}
int Hash(){//哈希判重 int s=0,k=1;for(int i=1;i<=4;i++)for(int j=1;j<=4;j++){s+=d[w].mp[i][j]*k;k*=3;}s%=3733799;if(!hash[s]){hash[s]=1;return 1;}return 0;
}
bool pd(int x,int y){int k=next[t];if(x>4||y>4||x==0||y==0)return 0;else if(d[t].mp[x][y]==k)return 1;return 0;
}
void sp(int &a,int &b){int t=a;a=b;b=t;}
void move(int x,int y){for(int i=0;i<4;i++){int p=x+xx[i],q=y+yy[i];if(pd(p,q)){for(int j=1;j<=4;j++)for(int k=1;k<=4;k++)d[w].mp[j][k]=d[t].mp[j][k];sp(d[w].mp[x][y],d[w].mp[p][q]);step[w]=step[t]+1;if(check()){cout<<step[w];flag=1;return;}if(Hash()){          if(next[t]==1)next[w++]=2;if(next[t]==2)next[w++]=1;}}}
}
void search(){while(t<w){for(int i=1;i<=4;i++)for(int j=1;j<=4;j++){if(d[t].mp[i][j]==0)move(i,j);if(flag)return;}t++;}
}
int main(){char x;for(int i=1;i<=4;i++)for(int j=1;j<=4;j++){cin>>x;if(x=='W')d[0].mp[i][j]=d[1].mp[i][j]=1;else if(x=='B')d[0].mp[i][j]=d[1].mp[i][j]=2;}search();return 0;
}