#include <bits/stdc++.h>
#define ll long long
#define F first
#define S second
#define pb push_back
using namespace std;
int n,m;
int main()
{
//freopen("input.txt","r",stdin);
//freopen("output.txt","w",stdout);
ios_base::sync_with_stdio(0); cin.tie(0);
cin >> n >> m;
char c[n][m];
string dp[n][m];
for(int i=0;i<n;i++)
for(int j=0;j<m;j++) cin >> c[i][j];
dp[0][0]=c[0][0];
for(int i=0;i<n;i++)
for(int j=0;j<m;j++)
if (i-1>=0 && j-1>=0)
dp[i][j]=min(dp[i-1][j],dp[i][j-1])+c[i][j];
else if (i-1>=0 && j-1<0) dp[i][j]=dp[i-1][j]+c[i][j];
else if (i-1<0 && j-1>=0) dp[i][j]=dp[i][j-1]+c[i][j];
cout << dp[n-1][m-1];
}
