#include<cstdio>#include<cstring>#include<algorithm>#include<queue>using namespace std;int r,c;typedef long long ll;ll map[400][400];struct Data{ int x,y; ll h; bool operator<(const Data ≠)const { return h>ne.h; } Data(){}; Data(int _x,int _y,ll _h) { x=_x; y=_y; h=_h; }};priority_queue<Data> Q;int dr[][2]={0,1,0,-1,1,0,-1,0};bool in(int x,int y){ return x>=1&&x<=r&&y>=1&&y<=c;}int main(){ while(scanf("%d%d",&c,&r)!=EOF) { for(int i=1;i<=r;i++) { for(int j=1;j<=c;j++) { scanf("%lld",&map[i][j]); } } while(!Q.empty()) Q.pop(); for(int i=1;i<=r;i++) { Q.push(Data(i,1,map[i][1])); Q.push(Data(i,c,map[i][c])); map[i][1]=-1; map[i][c]=-1; } for(int i=1;i<=c;i++) { Q.push(Data(1,i,map[1][i])); Q.push(Data(r,i,map[r][i])); map[1][i]=-1; map[r][i]=-1; } long long ans=0; while(!Q.empty()) { Data a=Q.top(),b; Q.pop(); for(int i=0;i<4;i++) { b.x=a.x+dr[i][0]; b.y=a.y+dr[i][1]; if(in(b.x,b.y)) { ll tp=map[b.x][b.y]; if(tp==-1) continue; else if(tp<a.h) { ans+=a.h-tp; } b.h=max(tp,a.h); Q.push(b); map[b.x][b.y]=-1; } } } printf("%lldn",ans); } return 0;}
