#include <bits/stdc++.h>

using namespace std;

int memo[110][110];
int mark[110][110];
int MAXINT = 0x3F3F3F3F;
int N, M;
int grid[110][110];

int DP(int i, int j, int sum) {
 if(i >= N || j >= M) return MAXINT;
 if(i < 0) return MAXINT;
 int &best = memo[i][j];
 if((sum+grid[i][j])>best) return MAXINT;
 sum += grid[i][j];
 best=min(DP(i-1, j+1, sum), min(DP(i, j+1, sum), DP(i+1, j+1, sum)));
 return best;
}

int main() {
  int i, j;
  cin >> N >> M;
  for (i=0; i<M; i++) {
    for(j=0; j<N; j++) {
      cin >> grid[j][i];
    }
  }
  int sol=0, temp=0;

  memset(memo, MAXINT, sizeof(memo));

  for(i=0; i<N; i++) {
    temp=DP(i, 0, 0);
    if(sol<temp) sol=temp;
  }
  cout << sol << endl;
}