#include <bits/stdc++.h>

#define FOR(i,a,b) for(int i= (a); i<((int)b); ++i)
#define RFOR(i,a) for(int i=(a); i >= 0; --i)
#define FOE(i,a) for(auto i : a)
#define ALL(c) (c).begin(), (c).end()
#define RALL(c) (c).rbegin(), (c).rend()
#define DUMP(x)  cerr << #x << " = " << (x) << endl;
#define SUM(x) std::accumulate(ALL(x), 0LL)
#define MIN(v) *std::min_element(v.begin(), v.end())
#define MAX(v) *std::max_element(v.begin(), v.end())
#define EXIST(v,x) (std::find(v.begin(), v.end(), x) != v.end())
#define BIT(n) (1LL<<(n))
#define UNIQUE(v) v.erase(unique(v.begin(), v.end()), v.end());

typedef long long LL;
template<typename T> using V = std::vector<T>;
template<typename T> using VV = std::vector<std::vector<T>>;
template<typename T> using VVV = std::vector<std::vector<std::vector<T>>>;

template<class T> inline T ceil(T a, T b) { return (a + b - 1) / b; }
template<class T> inline void print(T x) { std::cout << x << std::endl; }
template<class T> inline void print_vec(const std::vector<T> &v) { for (int i = 0; i < v.size(); ++i) {  if (i != 0) {std::cout << " ";} std::cout << v[i];} std::cout << "\n"; }
template<class T> inline bool inside(T y, T x, T H, T W) {return 0 <= y and y < H and 0 <= x and x < W; }
template<class T> inline double euclidean_distance(T y1, T x1, T y2, T x2) { return sqrt((x1 - x2) * (x1 - x2) + (y1 - y2) * (y1 - y2)); }
template<class T> inline double manhattan_distance(T y1, T x1, T y2, T x2) { return abs(x1 - x2) + abs(y1 - y2); }

const int INF = 1L << 30;
const double EPS = 1e-9;
const std::string YES = "YES", Yes = "Yes", NO = "NO", No = "No";
const std::vector<int> dy4 = { 0, 1, 0, -1 }, dx4 = { 1, 0, -1, 0 };    // 4近傍（右, 下, 左, 上）
const std::vector<int> dy8 = { 0, -1, 0, 1, 1, -1, -1, 1 }, dx8 = { 1, 0, -1, 0, 1, 1, -1, -1 };

using namespace std;

string lstrip(string s) {
    string ans = "";
    bool ok = false;
    FOE(c, s) {
        if (c != '0') {
            ans += c;
            ok = true;
        }
        else {
            if (ok) {
                ans += c;
            }
        }
    }
    return ans;
}

int main() {
    cin.tie(0);
	ios::sync_with_stdio(false);

	while (true) {
	    int W, H;
	    cin >> W >> H;
        if (W == 0 and H == 0) {
            break;
        }

	    vector<string> f(H);
	    FOR(i, 0, H) {
	        cin >> f[i];
	        FOR(j, 0, W) {
	            if ('A' <= f[i][j] and f[i][j] <= 'Z') {
	                f[i][j] = 'A';
	            }
	        }
	    }

	    vector<vector<string>> dp(H, vector<string>(W));
        FOR(y, 0, H) {
            FOR(x, 0, W) {
                if (f[y][x] != 'A') {
                    dp[y][x] = f[y][x];
                }
            }
        }

        FOR(y, 0, H) {
            FOR(x, 0, W) {
                if (f[y][x] == 'A') {
                    continue;
                }
                // down
                if (y + 1 < H and f[y + 1][x] != 'A') {
                    string a = dp[y][x] + f[y + 1][x];
                    string b = dp[y + 1][x];
                    a = lstrip(a);
                    b = lstrip(b);

                    if (a.size() == b.size()) {
                        dp[y + 1][x] = max(a, b);
                    }
                    else {
                        if (a.size() > b.size()) {
                            dp[y + 1][x] = a;
                        }
                    }
                }

                // left
                if (x + 1 < W and f[y][x + 1] != 'A') {
                    string a = dp[y][x] + f[y][x + 1];
                    string b = dp[y][x + 1];
                    a = lstrip(a);
                    b = lstrip(b);

                    if (a.size() == b.size()) {
                        dp[y][x + 1] = max(a, b);
                    }
                    else {
                        if (a.size() > b.size()) {
                            dp[y][x + 1] = a;
                        }
                    }
                }
            }
        }

        string tmp = "";
        FOR(y, 0, H) {
            FOR(x, 0, W) {
                string a = dp[y][x];
                a = lstrip(a);
                if (a.size() == tmp.size()) {
                    tmp = max(a, tmp);
                }
                else {
                    if (a.size() > tmp.size()) {
                        tmp = a;
                    }
                }
            }
        }
        if (tmp == "") {
            print(0);
        }
        else {
            print(tmp);
        }
	}

	return 0;
}


Measured memory_bytes: 3376