#include <bits/stdc++.h>
using namespace std;

#define ll unsigned long long int
#define MAX 1002

struct Cell{
    int x, y;
    ll sum;
    Cell(){}
    Cell(int _x, int _y, ll _sum){
        x=_x, y=_y, sum=_sum;
    }
};

class compare{
    public:
        bool operator()(Cell a, Cell b){
            return a.sum > b.sum;
        }
};

ll pathsum(ll grid[MAX][MAX], int n){

    if (n==0)   return 0;

    int visited[MAX][MAX];
    memset(visited, 0, sizeof(visited));

    priority_queue<Cell, vector<Cell>, compare> que;

    for (int i=0; i<n; i++){
        que.push(Cell(i, 0, grid[i][0]));
        visited[i][0] = 1;
    }

    ll min_sum = INT_MAX;

    while (!que.empty()){
        
        Cell cell = que.top();
        que.pop();

        if (cell.y==n-1) {
            min_sum = min(min_sum, cell.sum);
            return min_sum;
        }

        //down
        if (cell.x+1>=0 && cell.x+1<n && cell.y>=0 && cell.y<n && visited[cell.x+1][cell.y]==0){
            visited[cell.x+1][cell.y]=1;
            que.push(Cell(cell.x+1, cell.y, cell.sum+grid[cell.x+1][cell.y]));  
        }

        //right
        if (cell.x>=0 && cell.x<n && cell.y+1>=0 && cell.y+1<n && visited[cell.x][cell.y+1]==0){
            visited[cell.x+1][cell.y]=1;
            que.push(Cell(cell.x, cell.y+1, cell.sum+grid[cell.x][cell.y+1]));  
        }

        //up
        if (cell.x-1>=0 && cell.x-1<n && cell.y>=0 && cell.y<n && visited[cell.x-1][cell.y]==0){
            visited[cell.x-1][cell.y]=1;
            que.push(Cell(cell.x-1, cell.y, cell.sum+grid[cell.x-1][cell.y]));  
        }


    }

    return (min_sum==INT_MAX)?-1:min_sum;
}


int main() {

    int n;        
    cin >> n;
    ll grid[MAX][MAX];

    for (int i=0; i<n; i++){
        for (int j=0; j<n; j++){
            cin >> grid[i][j];
        }
    }

    cout << pathsum(grid, n) << endl;

    return 0;
}