#include <iostream>

#include <cstdio>

#include <string.h>

#include <algorithm>

using namespace std;

const int maxn =  ;

struct point{

  int loca,H;

  point( int a =  ,int c =  ){

    loca = a ; H = c ;

  }

  bool operator < (  const point &A ) const {

       return H < A.H||(H==A.H&&loca<A.loca) ;

  }

}hight[ maxn * maxn ];

struct node{

   int num , H ;

}map[ maxn ][ maxn ];

int per[ maxn * maxn ],n,m;

int xx[]={  , , , - };

int yy[]={  , -, ,  };

bool mark[ maxn ][ maxn ];

int F(int x){

    if( x == per[x] ) return x ;

    per[ x ] = F( per[ x ] );

    return per[ x ];

}

int main()

{

    while(scanf("%d%d",&n,&m)==){

           for( int i =  ; i < n ; ++ i )

               for( int j =  ; j < m ; ++ j ){

                  per[ i * m + j ] = i * m + j ;

                  map[ i ][ j ].num =  ;

                  scanf("%d",&map[i][j].H);

                  hight[ i * m + j ]= point( i * m + j , map[ i ][ j ].H );

                  mark[ i ][ j ] = false;

               }

               __int64 ans = ;

          sort( hight , hight + n*m );

          for( int i =  ; i < n*m ; ++ i ){

                bool falg = false ;

                int Tx = hight[ i ].loca/m;

                int Ty = hight[ i ].loca%m;

                mark[Tx][Ty] = true;

                for( int j =  ; j<  ; ++ j ){

                    int x = Tx + xx[ j ];

                    int y = Ty + yy[ j ];

                    if( x <  || y <  || x >= n || y >= m ){

                            falg = true;

                            continue;

                    }

                    int fa = F( x * m + y );

                    if( fa == hight[ i ].loca ) continue;

                    int fx = fa / m;

                    int fy = fa % m;

                    if( mark[ fx ][ fy ] == true && map[ fx ][ fy ].num !=  ){

                          ans += ( map[Tx][Ty].H - map[ fx ][ fy ].H ) * map[fx][fy].num;

                          per[ fa ] = hight[ i ].loca ;

                          map[ Tx ][ Ty ].num += map[ fx ][ fy ].num;

                    } else  if( map[ fx ][ fy ].num ==  ) {

                        falg = true ;

                        per[ fa ] = hight[ i ].loca;

                    }

                }

                if( falg ) map[ Tx ][ Ty ].num = ;

          }

          printf("%I64d\n",ans);

    }

    return ;

}