#include<cstdio>#include<cstring>#include<algorithm>using namespace std;bool mark[105][105];int map[105][105];int n;bool dfs(int x,int y,int mmin,int len){ mark[x][y]=true; if(x==n&&y==n) return true; bool flag=false; if(x<n&&!mark[x+1][y]&&map[x+1][y]<=mmin+len&&map[x+1][y]>=mmin) flag|=dfs(x+1,y,mmin,len); if(x>1&&!mark[x-1][y]&&map[x-1][y]<=mmin+len&&map[x-1][y]>=mmin) flag|=dfs(x-1,y,mmin,len); if(y>1&&!mark[x][y-1]&&map[x][y-1]<=mmin+len&&map[x][y-1]>=mmin) flag|=dfs(x,y-1,mmin,len); if(y<n&&!mark[x][y+1]&&map[x][y+1]<=mmin+len&&map[x][y+1]>=mmin) flag|=dfs(x,y+1,mmin,len); return flag;}bool solve(int mid){ int t=map[1][1]; for(int i=max(t-mid,0);i<=t;i++) { memset(mark,false,sizeof(mark)); if(dfs(1,1,i,mid)) return true; } return false;}int main(){ while(scanf("%d",&n)!=EOF) { for(int i=1;i<=n;i++) for(int j=1;j<=n;j++) scanf("%d",&map[i][j]); int ans=0,ll,rr,mid; for(ll=0,rr=110;ll<=rr;) { mid=(ll+rr)>>1; if(solve(mid)) { ans=mid; rr=mid-1; } else { ll=mid+1; } } printf("%dn",ans); } return 0;}
