#include<bits/stdc++.h>
using namespace std;
const int N=405;
int n;
int mp[N][N];
vector<int>aa,bb;
int ans=0;
struct edge
{
    int u,v,c;
};
bool cmp(edge a,edge b)
{
    return a.c>b.c;
}
int fa[N];
int fir[N],nex[4*N],to[4*N];
int dfn[N],low[N],tot,col,co[N];
bool in[N];
list<int>s;
inline int rev(int x)
{
    if(x>n)return x-n;
    else return x+n;
}
int cnt=1;
void dfs(int u)
{
    dfn[u]=low[u]=++tot;
    in[u]=1;
    s.push_back(u);
    for(int i=fir[u];i;i=nex[i])
    {
        int v=to[i];
        if(!dfn[v])
        {
            dfs(v);
            low[u]=min(low[u],low[v]);
        }
        else if(in[v])
        {
            low[u]=min(low[u],dfn[v]);
        }
    }
    if(dfn[u]==low[u])
    {
        co[u]=++col;
        in[u]=0;
        while(s.back()!=u)
        {
            
            co[s.back()]=col;
            in[s.back()]=0;
            s.pop_back();
        }
        s.pop_back();
    }
}
void insert(int u,int v)
{
    nex[++cnt]=fir[u];
    fir[u]=cnt;
    to[cnt]=v;
}
int find(int x)
{
    if(fa[x]==x)return x;
    return fa[x]=find(fa[x]);
}
bool check(int a,int b)
{
    memset(dfn,0,sizeof(dfn));
    memset(fir,0,sizeof(fir));
    cnt=0;
    tot=0;
    col=0;
    for(int i=1;i<=n;i++)
    {
        for(int j=1;j<=n;j++)
        {
            if(mp[i][j]>a)
            {
                insert(i,rev(j));
                insert(j,rev(i));
            }
            if(mp[i][j]>b)
            {
                insert(rev(i),j);
                insert(rev(j),i);
            }
        }
    }
    s.clear();
    for(int i=1;i<=2*n;i++)
    {
        if(dfn[i]==0)
        {
            dfs(i);
        }
    }
    for(int i=1;i<=2*n;i++)
    {
        if(co[i]==co[rev(i)])
        {
            return 0;
        }
    }
    return 1;
}
int main()
{
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    cin>>n;
    int mx=0;
    vector<edge>tp;
    for(int i=1;i<=n;i++)
    {
        for(int j=i+1;j<=n;j++)
        {
            cin>>mp[i][j];
            tp.push_back({i,j,mp[i][j]});
            mp[j][i]=mp[i][j];
            mx=max(mx,mp[i][j]);
            
        }
    }
    int ans=2e9+7;
    sort(tp.begin(),tp.end(),cmp);
    for(int i=1;i<=2*n;i++)
    {
        fa[i]=i;
    }
    int cnt=0;
    for(int i=0;i<tp.size();i++)
    {
        int u=tp[i].u,v=tp[i].v;
        bool tg=0;
        if(find(u)==find(rev(v)))continue;
        else
        {
            fa[find(u)]=find(rev(v));
            fa[find(rev(v))]=find(u);
            if(find(u)==find(rev(u))||find(v)==find(rev(v)))
            {
                tg=1;
                
            }
        }
        cnt++;
        if(cnt>n)exit(114514);
        //cerr<<tp[i].c<<"??\n";
        int l=0,r=tp[i].c;
        while(l<=r)
        {
            int mid=(l+r)>>1;
            if(check(tp[i].c,mid))
            {
                ans=min(ans,mid+tp[i].c);
                r=mid-1;
            }
            else l=mid+1;
        }
        if(tg)break;
    }
    if(check(0,0))
    {
        ans=min(ans,0);
    }
    cout<<ans;
}