#include 

using namespace std;
int n, m;
int mat[55][55];
int dp[55][55];
int max_sum(int i, int j) {
    if(i == n - 1 and j == m - 1) {
        return mat[i][j];
    }
    if(dp[i][j] != -1) {
        return dp[i][j];
    }
    int result = 0;
    if(i + 1 < n) {
        result = max(result, max_sum(i + 1, j) + mat[i][j]);
    }
    if(j + 1 < m) {
        result = max(result, max_sum(i, j + 1) + mat[i][j]);
    }
    return dp[i][j] = result;
}
int main() {
    cin >> n >> m;
    
    for(int i = 0; i < n; i++) {
        for(int j = 0; j < m; j++) {
            cin >> mat[i][j];
            dp[i][j] = -1;
        }
    }
    cout << max_sum(0, 0) << endl;
    return 0;
}
// f(0, 0) = f(1, 0) f(0, 1)
// f(1, 0) = f(2, 0) f(1, 1)
// f(0, 1) = f(1, 1) f(2, 0)