#include <stdio.h>int max(int a, int b, int c) { return a > b ? (a > c ? a : c) : (b > c ? b : c);}int main(void) { int n, m; int table[1000][1000]; scanf("%d %d", &n, &m); for (int i=0; i<n; i++) { for (int j=0; j<m; j++) { scanf("%d", &table[i][j]); } } for (int i=0; i<n; i++) { for (int j=0; j<m; j++) { if (i == 0 && j == 0) continue; else if (i == 0) table[i][j] += table[i][j-1]; else if (j == 0) table[i][j] += table[i-1][j]; else table[i][j] += max(table[i-1][j-1], table[i-1][j], table[i][j-1]); } } printf("%d", table[n-1][m-1]); return 0;}