#include<iostream>using namespace std;int map[21][21];int d[21][21];int N, M;int dp(int i, int j){    if(d[i][j]!=0)        return d[i][j];    if(i==N-1&&j==M-1)        return d[i][j]=map[i][j];    if(i==N-1&&j!=M-1)        return d[i][j]=map[i][j] + dp(i,j+1);    if(j==M-1&&i!=N-1)        return d[i][j]=map[i][j] + dp(i+1,j);    return d[i][j]=map[i][j]+(dp(i,j+1)>dp(i+1,j)?dp(i,j+1):dp(i+1,j));}int main(){    cin>>N>>M;    for(int i=0; i<N; i++)        for(int j=0; j<M; j++)            cin>>map[i][j];    cout<<dp(0,0)<<endl;    return 0;}