#include<bits/stdc++.h>
using namespace std;
const long long MaxN = 1e2 + 5;
long long n,a[MaxN][MaxN][MaxN],d[MaxN][MaxN][MaxN];
void dijikstra()
{
    priority_queue<tuple<long long, long long, long long, long long>,
                    vector<tuple<long long, long long, long long, long long>>,
                    greater<tuple<long long, long long, long long, long long>>> pq;
    d[1][1][1]=0;
    pq.push({0,1,1,1});
    while(!pq.empty())
    {
        long long dxyz= get<0>(pq.top());
        long long x= get<1>(pq.top());
        long long y= get<2>(pq.top());
        long long z= get<3>(pq.top());
        pq.pop();

        if(dxyz!=d[x][y][z]) continue;

        if(x>1&&d[x-1][y][z]>d[x][y][z]+a[x-1][y][z])
        {
            d[x-1][y][z]=d[x][y][z]+a[x-1][y][z];
            pq.push({d[x-1][y][z],x-1,y,z});
        }

        if(y>1&&d[x][y-1][z]>d[x][y][z]+a[x][y-1][z])
        {
            d[x][y-1][z]=d[x][y][z]+a[x][y-1][z];
            pq.push({d[x][y-1][z],x,y-1,z});
        }

        if(z>1&&d[x][y][z-1]>d[x][y][z]+a[x][y][z-1])
        {
            d[x][y][z-1]=d[x][y][z]+a[x][y][z-1];
            pq.push({d[x][y][z-1],x,y,z-1});
        }

        if(x<n&&d[x+1][y][z]>d[x][y][z]+a[x+1][y][z])
        {
            d[x+1][y][z]=d[x][y][z]+a[x+1][y][z];
            pq.push({d[x+1][y][z],x+1,y,z});
        }

        if(y<n&&d[x][y+1][z]>d[x][y][z]+a[x][y+1][z])
        {
            d[x][y+1][z]=d[x][y][z]+a[x][y+1][z];
            pq.push({d[x][y+1][z],x,y+1,z});
        }

        if(z<n&&d[x][y][z+1]>d[x][y][z]+a[x][y][z+1])
        {
            d[x][y][z+1]=d[x][y][z]+a[x][y][z+1];
            pq.push({d[x][y][z+1],x,y,z+1});
        }

    }
}
void input()
{
    cin >> n;
    for (long long i=1; i<=n; i++)
    {
        for (long long j=1; j<=n; j++)
        {
            for (long long k=1; k<=n; k++)
            {
                cin >> a[i][j][k];
            }
        }
    }
}
void solve()
{
    memset(d,0x3f,sizeof(d));
    dijikstra();
    cout << d[n][n][n];
}
int main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    input();
    solve();
}