QBMAX

#include <iostream>
#include <cmath>
#include <iomanip>

using namespace std;

int max_abc(int a,int b, int c)
{
    return max(a,max(b,c));
};
int main()
{
    int n,m,i,j,max;
    cin>>n>>m;
    int a[n+2][m+2], b[n+2][m+2];

    for (j=0; j<=m+1;j++)
        b[0][j] = b[n+1][j] = 0;
    for (i=0; i<=n+1; i++)
        b[i][0] = b[i][m+1] = 0;

    for (i=1; i<=n; i++)
        for (j=1; j<=m; j++)
            cin>>a[i][j];

    max = a[1][1];
    for (i=1; i<=n; i++)
    {
        if (max < a[i][1]) max = a[i][1];
        b[i][1] = a[i][1];
    }

    for (j=1; j<=m; j++)
    {
        for (i=1; i<=n; i++)
            b[i][j] = a[i][j] + max_abc(b[i-1][j-1], b[i][j-1], b[i+1][j-1]);
        max = b[1][j];
        for (i=2; i<=n; i++)
            if (max < b[i][j]) max = b[i][j];
    }

    cout<<max;
    return 0;
}