这里是代码：```cpp
#include<bits/stdc++.h>
using namespace std;
int main(){
typedef __int128 ll;
const int mx=81;
int n,m,a[mx][mx];
ll f[mx][mx],sum=0;
void write(ll x){
if(x<0)putchar('-'),x=-x;
if(x>9)write(x/10);
putchar(x%10+'0');
}
ll solve(int r){
memset(f,0,sizeof(f));
for(int i=1;i<=m;i++)f[i][1]=a[r][i]*2;
for(int j=2;j<=m;j++)for(int i=1;i<=m-j+1;i++)f[i][j]=max(f[i][j-1]+a[r][i+j-1],f[i+1][j-1]+a[r][i])*2;
return f[1][m];
}
int main(){
cin>>n>>m;
for(int i=1;i<=n;i++){
for(int j=1;j<=m;j++)cin>>a[i][j];
sum+=solve(i);
}
write(sum);
return 0;
}
