#include <bits/stdc++.h>
#define int long long
#define endl '\n'
#define REP(i,a,b)for(int i=a;i<b;i++)
#define fi first
#define se second
using namespace std;
using pii=pair<int, int>;
int color[1000][1000];
bool visited[1000][1000];
int on=0;
int col=-1;
int h, w;
void bfs() {
queue<pii> q;
q.push({0,0});
while(q.size()){
auto top=q.front();
q.pop();
if(top.fi<0)continue;
if(top.fi>=h)continue;
if(top.se<0)continue;
if(top.se>=w)continue;
if(visited[top.fi][top.se])continue;
visited[top.fi][top.se]=true;
if((color[top.fi][top.se]!=col) && (color[top.fi][top.se]!=(-1))){
continue;
}
if(color[top.fi][top.se]!=(-1))on--;
color[top.fi][top.se]=-1;
q.push({top.fi+1, top.se});
q.push({top.fi-1, top.se});
q.push({top.fi, top.se+1});
q.push({top.fi, top.se-1});
}
}
int main() {
cin>>h>>w;
assert(max(h, w)<1000);
REP(i,0,h){
REP(j,0,w){
char c;cin>>c;
if(c=='.')color[i][j]=0;
if(c=='R')color[i][j]=1;
if(c=='F')color[i][j]=2;
if(color[i][j])on++;
}
}
col=color[0][0];
int ans=0;
// on=1;
while(true){
ans++;
bfs();
memset(visited,0,sizeof visited);
bool clear=true;
REP(i,0,h){
REP(j,0,w){
if(color[i][j]>=1)clear=false;
// cout<<color[i][j]<<" ";
// if(color[i][j]!=-1)cout<<" ";
}
// cout<<endl;
}
if(clear)break;
col = 3-col;
}
cout<<ans<<endl;
}
Compilation message
cc1plus: error: '::main' must return 'int'
