J

#include <iostream>

using namespace std;

const unsigned MAXN = 1001;
long long m[MAXN][MAXN], n, k, maxDiff, maxD, md[5000], ind = 0;

int main(){
    while( cin >> n >> k ){
           //memset( m, 0, n*n );
           /*
           for( int i=1; i<=n; i++ ){
                m[i][0] = -1000;
                m[0][i] = -1000;
           }
           */
           maxDiff = maxD = 0;

           for( int i=1; i<=n; i++ ){
                for( int j=1; j<=n; j++ ){
                     cin >> m[i][j];
                   /*  if( i == 1 ) {
                           maxDiff = m[i][j]+ m[i][j-1];
                           if( maxDiff > maxD ) maxD = maxDiff;
                     }
                     if( j == 1 ) {
                           maxDiff = m[i][j]+ m[i-1][j];
                           if( maxDiff > maxD ) maxD = maxDiff;
                     }

                     if(m[i-1][j] > m[i][j-1]){
                                  maxDiff = m[i][j]+ m[i-1][j];
                                  if( maxDiff > maxD ) maxD = maxDiff;
                      }
                      else {
                                  maxDiff = m[i][j]+ m[i][j-1];
                                  if( maxDiff > maxD ) maxD = maxDiff;
                      }     */
                }
           }

           for( int i=1; i<=n; i++ ){
                for( int j=1; j<=n; j++ ){
                     if( i == 1 ) {
                           m[i][j] += m[i][j-1];
                     }
                     if( j == 1 ) {
                           m[i][j] += m[i-1][j];
                     }
                     if(m[i-1][j] > m[i][j-1] && j != 1){
                           md[ind++] = i;
                           m[i][j] += m[i-1][j];
                     }
                     else if (i != 1) {
                          md[ind++] = j;
                           m[i][j] += m[i][j-1];
                }
           }
           cout << ( m[n][n] + k*maxD ) << endl;
    }
    return 0;
}
/*
3 1
1 1 0
1 1 0
1 1 1
4 4
1 1 1 0
1 0 1 0
1 1 1 0
0 0 1 1
4 4
1 1 1 0
1 0 1 0
1 1 0 0
0 0 1 1
4 4
-1 -1 -1 0
-1 0 -1 0
-1 -1 0 0
0 0 -1 -1
4 4
-1 -1 -1 -1
-1 -1 -1 -1
-1 -1 -1 -1
-1 -1 -1 -1
3 1
1 1 0
1 1 0
1 1 1
3 1
1000 -1000 0
-1000 1000 0
1 1 1
2 3
0 10
0 20
2 4
0 10
0 20
2 0
1 4
6 20
2 1
1 4
6 20
2 2
1 4
6 20
*/