[ABC007C] 幅優先探索

#include <iostream>
using namespace std;
int a[123][123],n,m,x1,y1,x2,y2;
void dfs(int x,int y,int s){
    if(a[x][y]==-1)return;
    if(a[x][y]!=0&&a[x][y]<=s)return;
    a[x][y]=s,s+=1,dfs(x+1,y,s);
    dfs(x-1,y,s),dfs(x,y+1,s),dfs(x,y-1,s);
}
int main(){
    char c;
    for(int i=0;i<104;i++)for(int j=0;j<104;j++)a[i][j]=-1;
    cin>>n>>m>>x1>>y1>>x2>>y2;
    for(int i=1;i<=n;i++){
       for(int j=1;j<=m;j++){
      	  cin>>c;
      	  if(c=='.')a[i][j]=0;
      	  else a[i][j]=-1;
       } 
    }dfs(x1,y1,0);
    cout<<a[x2][y2]<<endl;
}