#include <iostream>
#include <string>
#include <cstdlib>
#include <cctype>

using namespace std;

void solve(int w,int h,string data[]);
const string maxnum(const string &a,const string &b);

int main(void){
  int w,h;
  string *data;
  
  while(true){
    cin >> w;
    cin >> h;
    if(w==0 && h == 0) break;
    data = new string[h];
    for(int i=0;i<h;i++){
      cin >> data[i];
    }
    
    solve(w,h,data);
    
    delete [] data;
  }
  
  
  
}

void solve(int w,int h,string data[]){
  string **score = new string*[h];
  string maxscore="0";
  char c;
  int i,j;
  //allocate
  for(i=0;i<h;i++){
    score[i] =new string[w];
  }
  
  //solve
  for(i=0;i<h;i++){
    for(j=0;j<w;j++){
      c = data[i][j];
      if(!isdigit(c)){
	score[i][j]="0";
	continue;
      }
      score[i][j]=string(1,c);
      
      if(i!=0 && score[i-1][j]!="0"){
	score[i][j] =maxnum(score[i][j],score[i-1][j]+string(1,c));
      }
      
      if(j!=0 && score[i][j-1]!="0"){
	score[i][j] =maxnum(score[i][j],score[i][j-1]+string(1,c));
      }
      maxscore = maxnum(maxscore,score[i][j]);
      
    }
    
    
  }
  //print
  cout << maxscore << endl;
  //delete

  for(i=0;i<h;i++){
    delete[] score[i];
  }
  delete[] score;
}


const string maxnum(const string &a,const string &b){
  int as,bs;
  as = a.length();
  bs = b.length();
  if(as > bs) return a;
  if(as < bs) return b;
  if(a > b) return a;
  return b;
  
  
}