#include<iostream>
#include<algorithm>
using namespace std;
const int N=110;
int n,s_x,s_y,e_x,e_y,h,t;
char w[N][N];
bool fl[N][N];
struct que{
    int x,y,dist;
    char c;
} q[N*N];

///广搜，自写队列
void bfs(){
    int dx[4]={-1,0,1,0},dy[4]={0,1,0,-1};
    h=1,t=1;//头尾指针
    q[t].x=s_x,q[t].y=s_y,q[t].dist=0;
    q[t].c=' ';
    fl[s_x][s_y]=true;
    t++;
    while(h<t){
        if(q[h].x==e_x&&q[h].y==e_y){
            cout<<q[h].dist<<endl;
            return;
        }
        for(int i=0;i<4;i++){
            int u=q[h].x+dx[i],v=q[h].y+dy[i];
            if(u<1||u>n||v<1||v>n||w[u][v]==q[h].c||fl[u][v]) continue;
            q[t].x=u,q[t].y=v,q[t].c=w[u][v];
            q[t].dist=q[h].dist+1;
            fl[u][v]=true;///最容易忘记!!!!!写到for循环外就错了
            t++;
        }
        h++;
    }
    cout<<-1<<endl;
    return;
}
int main(){
    cin>>n;
    for(int i=1;i<=n;i++){
        for(int j=1;j<=n;j++){
            cin>>w[i][j];
            if(w[i][j]=='A'){
                s_x=i;
                s_y=j;
            }
            if(w[i][j]=='B'){
                e_x=i;
                e_y=j;
            }
        }
    }
    bfs();
    return 0;
}