#include <iostream>
#include <algorithm>
#include <string>
#include <cstdlib>

using namespace std;

int h, w;
char input[100][100];
string table[100][100];
string ans;

string& comp(string& a, string& b) {
  if(a.size() != b.size()) {
    return (a.size() > b.size()) ? a : b;
  }
  if(a > b)
    return a;
  return b;
}

void Run(int x, int y) {
  char c = input[x][y];
  if('0' <= c && c <= '9') {
    string& s = comp(table[x+1][y], table[x][y+1]);
    table[x][y] = c + s;
    string ss = table[x][y];
    int i;
    for(i = 0; i < (int)ss.size(); ++i)
      if(ss[i] != '0')
	break;
    ss = ss.substr(i);
    ans = comp(ans, ss);
  }
}

int main() {
  while(cin >> w >> h && w && h) {
    ans = "";
    for(int i = 0; i < 100; ++i)
      for(int j = 0; j < 100; ++j)
	table[i][j] = "";
    for(int y = 0; y < h; ++y)
      for(int x = 0; x < w; ++x)
	cin >> input[x][y];
    for(int y = h-1; y >= 0; --y)
      for(int x = w-1; x >= 0; --x)
	Run(x, y);
    cout << ans << endl;
  }
}