#include <iostream>
#include <string>
#include <algorithm>
#include <math.h>
#include <vector>
#include <map>
#include <set>
#include <deque>
#include <queue>
#include <cstdio>
#include <iomanip>
#include <list>

#define PI 3.14159265358979323846
#define mod 1000000007
#define pow9 1000000000
#define INF (1 << 30)

using namespace std;


int main() {
	int h, w;
	cin >> h >> w;
	vector<vector<char>> s(h, vector<char>(w));
	for (int i = 0; i < h; i++) {
		for (int j = 0; j < w; j++) {
			cin >> s[i][j];
		}
	}

	vector<string> ans(h * w + 1);

	ans[1] = s[0][0];

	for (int i = 0; i < h; i++) {
		for (int j = 0; j < w; j++) {

			if (i == 0 && j == 0) continue;
			else if (i == 0) {
				ans[i * w + j + 1] = ans[i * w + j] + s[i][j];
			}
			else if (j == 0) {
				ans[i * w + j + 1] = ans[(i - 1) * w + j + 1] + s[i][j];
			}

			else if (ans[(i - 1) * w + j + 1] >= ans[i * w + j]) {
				ans[i * w + j + 1] = ans[i * w + j] + s[i][j];
			}
			else {
				ans[i * w + j + 1] = ans[(i - 1) * w + j + 1] + s[i][j];
			}
		}
	}

	cout << ans[h * w] << endl;


}