#include <iostream>
#include <string>
#include <queue>
#include <stack>
#include <algorithm>
#include <list>
#include <vector>
#include <complex>
#include <utility>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <climits>
#include <bitset>
#include <ctime>
#include <map>
#include <unordered_map>
#include <set>
#include <unordered_set>
#include <cassert>
#include <cstddef>
#include <iomanip>
#include <numeric>
#include <tuple>
#include <sstream>
#include <fstream>

using namespace std;
#define REP(i, n) for (int (i) = 0; (i) < (n); (i)++)
#define FOR(i, a, b) for (int (i) = (a); (i) < (b); (i)++)
#define RREP(i, a) for(int (i) = (a) - 1; (i) >= 0; (i)--)
#define FORR(i, a, b) for(int (i) = (a) - 1; (i) >= (b); (i)--)
#define DEBUG(C) cerr << #C << " = " << C << endl;
using LL = long long;
using VI = vector<int>;
using VVI = vector<VI>;
using VL = vector<LL>;
using VVL = vector<VL>;
using VD = vector<double>;
using VVD = vector<VD>;
using PII = pair<int, int>;
using PDD = pair<double, double>;
using PLL = pair<LL, LL>;
using VPII = vector<PII>;
template<typename T> using VT = vector<T>;
#define ALL(a) begin((a)), end((a))
#define RALL(a) rbegin((a)), rend((a))
#define SORT(a) sort(ALL((a)))
#define RSORT(a) sort(RALL((a)))
#define REVERSE(a) reverse(ALL((a)))
#define MP make_pair
#define FORE(a, b) for (auto &&a : (b))
#define FIND(s, e) ((s).find(e) != (s).end())
#define EB emplace_back
template<typename T>inline bool chmax(T &a,T b){if(a<b){a=b;return true;}return false;}
template<typename T>inline bool chmin(T &a,T b){if(a>b){a=b;return true;}return false;}

const int INF = 1e9;
const int MOD = INF + 7;
const LL LLINF = 1e18;

void init();
void last();

void init() {

}

const int MAX = 75;
char C[MAX][MAX];
string dp[MAX][MAX];

void comp(string &a, string b) {
    if (a.length() < b.length()) a = b;
    else if (a.length() == b.length()) {
        const int L = a.length();
        for (int i = 0; i < L; i++) {
            if (a[i] < b[i]) {
                a = b;
                return;
            } else if (a[i] > b[i]) {
                return;
            }
        }
    }
}

void solve(int H, int W) {
    for (int i = 0; i < H; i++) {
        scanf("%s", C[i]);
    }
    auto inside = [&](int h, int w) {
        return 0 <= h && h < H && 0 <= w && w < W;
    };
    for (int i = 0; i < H; i++) {
        for (int j = 0; j < W; j++) {
            dp[i][j] = "";
        }
    }
    string ans = "";
    for (int i = 0; i < H; i++) {
        for (int j = 0; j < W; j++) {
            if (isdigit(C[i][j])) {
                dp[i][j] = C[i][j];
                if (inside(i - 1, j)) comp(dp[i][j], dp[i - 1][j] + C[i][j]);
                if (inside(i, j - 1)) comp(dp[i][j], dp[i][j - 1] + C[i][j]);
            }
            if (dp[i][j] == "0") dp[i][j] = "";
            comp(ans, dp[i][j]);
            //cout<<"(i, j, dp[i][j]) = ("<<i<<", "<<j<<", "<<dp[i][j]<<")"<<endl;
        }
    }
    printf("%s\n", ans.c_str());
}

void last() {
    exit(0);
}

int main(void) {
	int a, b, c, x, y, z, n, m, p;
	string s;
	while (cin >> n >> m, n) {
		solve(m, n);
		//break;
	}
    last();
}

Measured memory_bytes: 3360