tijei

#include<bits/stdc++.h>
using namespace std;
int n,m,a[55][55],f[55][55][55];
int main(){
scanf("%d%d",&n,&m);
for(int i=1;i<=n;i++){
for(int j=1;j<=m;j++){
scanf("%d",&a[i][j]);
}
}
memset(f,0xcf,sizeof(f));
f[1][1][1]=0;
for(int i=1;i<=n;i++){
for(int j=1;j<=m;j++){
for(int x=i+1;x<=n;x++){
int y=i+j-x;
f[i][j][x]=a[i][j]+a[x][y]+
max(max(f[i-1][j][x-1],f[i-1][j][x]),
max(f[i][j-1][x-1],f[i][j-1][x]));
}
}
}
f[n][m][n]=f[n-1][m][n];
printf("%d\n",f[n-1][m][n]);
return 0;
}