Sewer

#include<stdio.h>
#include<vector>
#include<queue>
using namespace std;

struct pos{
    int I,J;
};

struct edge{
    pos now;
    pos parent;
    int pDist;
    bool operator < (const edge& rhs)const
    {
        return pDist > rhs.pDist;
    }
};

bool InB(int I,int N)
{
    return (I >= 1 && I <= N);
}

int main()
{
    int n,m;
    scanf("%d %d",&n,&m);
    vector<pos> adj[n+1][m+1];
    for(int i = 1 ; i <= n ; i++){
        for(int j = 1 ; j <= m ; j++){
            char c;
            scanf(" %c",&c);
            if(c == 'B'){
                adj[i][j].push_back({i+1,j});
                adj[i][j].push_back({i,j+1});
                if(InB(i+1,n))adj[i+1][j].push_back({i,j});
                if(InB(j+1,m))adj[i][j+1].push_back({i,j});
            }
            else if(c == 'D'){
                adj[i][j].push_back({i+1,j});
                if(InB(i+1,n))adj[i+1][j].push_back({i,j});
            }
            else if(c == 'R'){
                adj[i][j].push_back({i,j+1});
                if(InB(j+1,m))adj[i][j+1].push_back({i,j});
            }
        }
    }
    priority_queue<edge> pq;
    pq.push({{1,1},{0,0},1});
    bool visited[n+1][m+1];for(int i = 0 ; i <= n ; i++)for(int j = 0 ; j <= m ;j ++)visited[i][j] = false;

    int ansDist = 2e9;
    int ansI;
    int ansJ;
    while(!pq.empty()){
        int uI = pq.top().now.I;
        int uJ = pq.top().now.J;
        int PuI = pq.top().parent.I;
        int PuJ = pq.top().parent.J;
        int uPd = pq.top().pDist;
        pq.pop();
        if(visited[uI][uJ]){
            if(ansDist > uPd){
                ansDist = uPd;
                ansI = uI;
                ansJ = uJ;
            }
            continue;
        }
        visited[uI][uJ] = true;

        for(int i = 0 ; i < adj[uI][uJ].size();i++){
            int vI = adj[uI][uJ][i].I;
            int vJ = adj[uI][uJ][i].J;
            if(InB(vI,n) && InB(vJ,m) && (vI != PuI || vJ != PuJ)/* && !visited[vI][vJ]*/){
                pq.push({{vI,vJ},{uI,uJ},uPd+1});
            }
        }
    }
    printf("%d\n%d %d",ansDist,ansI,ansJ);
    return 0;
}