#include<iostream>
#include<algorithm>
using namespace std;
int main(){
  int h,w,i,j,k,c,ans = 0;cin >> h >> w;
  int my[h][w],mh[w][h];char s[h][w];
  for(i=0;i<h;i++){
    c = 0;
    for(j=0;j<w;j++){
      cin >> s[i][j];
      if(s[i][j]=='.') c++;
      else{
        my[i][j] = -10000;
        for(k=j-1;k>=j-c;k--) my[i][k] = c;
        c = 0;
      }
    }
    for(k=w-1;k>=w-c;k--) my[i][k] = c;
  }
  for(i=0;i<w;i++){
    c = 0;
    for(j=0;j<h;j++){
      if(s[j][i]=='.') c++;
      else{
        mh[i][j] = -10000;
        for(k=j-1;k>=j-c;k--) mh[i][k] = c;
        c = 0;
      }
    }
    for(k=h-1;k>=h-c;k--) mh[i][k] = c;
  }
  for(i=0;i<h;i++){
    for(j=0;j<w;j++) ans = max(ans,my[i][j]+mh[j][i]);
  }
  cout << ans-1 << endl;
}