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

using namespace std;

bool larger(string& s1,string& s2){
	int l1,l2,i;
	l1 = s1.length();
	l2 = s2.length();
	
	if(l1>l2) return true;
	if(l1<l2) return false;
	
	//l1==l2
	for(i=0;i<l1;i++){
		if(s1[i]>s2[i]) return true;
		if(s1[i]<s2[i]) return false;
	}
	
	//s1==s2
	return false;
}

void normalize(string& s){
	if(s.empty()) return;
	
	int i;
	i = s.find_first_not_of('0');

	if(i>=0) s = s.substr(i);
	else s = "";
	return;
}

void calc_cell(char** matrix,string** table,int i,int j){
	char tmp[2];
	
	//cout << "error" << " " << i << " " << j << endl;
	
	if(isdigit(matrix[i][j])){
		if(larger(table[i+1][j],table[i][j+1])){
			table[i][j] = string(1,matrix[i][j]) + table[i+1][j];
			//cout << table[i][j] << endl;
		}
		else{
			table[i][j] = string(1,matrix[i][j]) + table[i][j+1];
			//cout << table[i][j] << endl;
		}
	}
	else{
		table[i][j] = "";
	}
}

string calc_max(char** matrix,string** table,int w,int h){
	int i,j,k;
	string max,tmp;
	max = "";
	i = h-1;
	j = w-1;
	
	for(k=0;k<=w;k++){
		table[h][k] = "";
	}
	for(k=0;k<=h;k++){
		table[k][w] = "";
	}
	
	do{
		calc_cell(matrix,table,i,j);
		tmp = table[i][j];
		normalize(tmp);
		if(larger(tmp,max)) max = tmp;
		
		for(k=j-1;k>=0;k--){
			calc_cell(matrix,table,i,k);
			tmp = table[i][k];
			normalize(tmp);
			if(larger(tmp,max)) max = tmp;
		}
		
		for(k=i-1;k>=0;k--){
			calc_cell(matrix,table,k,j);
			tmp = table[k][j];
			normalize(tmp);
			if(larger(tmp,max)) max = tmp;
		}
		
		if(i>=1) i--;
		if(j>=1) j--;
		
	}while(i>0 || j>0);
	
	return max;
}

int main(void){
	int w,h;
	char** matrix;
	string** table;
	string max;
	int i,j;
	cin >> w >> h;
	while(h!=0 && w!=0){
		matrix = new char*[h];
		table = new string*[h+1];
		for(i=0;i<h;i++){
			matrix[i] = new char[w];
		}
		for(i=0;i<h+1;i++){
			table[i] = new string[w+1];
		}
		
		for(i=0;i<h;i++){
			for(j=0;j<w;j++){
				cin >> matrix[i][j];
			}
		}
		
		max = calc_max(matrix,table,w,h);
		
		for(i=0;i<h;i++){
			delete [] matrix[i];
		}
		for(i=0;i<h+1;i++){
			delete [] table[i];
		}
		delete [] matrix;
		delete [] table;
		
		cout << max << endl;
		
		cin >> w >> h;
	}
}