def I():return int(input())
def MAP():return map(int,input().split())
def MAPs():return map(str,input().split())
def LI(): return list(map(int,input().split()))
def TPL(): return tuple(map(int,input().split()))
def S():return input()
from collections import defaultdict,Counter,deque
from copy import deepcopy
from heapq import heapify,heappop,heappush
from bisect import bisect_left,bisect_right
from itertools import accumulate,product,permutations,combinations
from math import gcd,ceil,floor,sqrt
inf=10**18

h,w=MAP()
g=[S() for _ in range(h)]
dp=[['']*w for _ in range(h)]
dp[0][0]=g[0][0]
for i in range(h):
    for j in range(w):
        if i==j==0:
            continue
        if i==0:
            dp[i][j]=dp[i][j-1]+g[i][j]
        elif j==0:
            dp[i][j]=dp[i-1][j]+g[i][j]
        else:
            if dp[i-1][j]<dp[i][j-1]:
                dp[i][j]=dp[i-1][j]+g[i][j]
            else:
                dp[i][j]=dp[i][j-1]+g[i][j]
print(dp[-1][-1])