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#include <iostream>
#include <cstdio>
#include <string>
#include <vector>
#include <set>
#include <map>
#include <queue>
#include <cmath>
#include <algorithm>
#include <sstream>
#include <stack>
#include <cstring>
#include <iomanip>
#include <cassert>
using namespace std;
#define pb push_back
#define INF 1001001001
#define FOR(i,n) for(int (i)=0;(i)<(n);++(i))
#define FORI(i,n) for(int (i)=1;(i)<=(n);++(i))
#define mp make_pair
#define pii pair<int,int>
#define ll long long
#define vi vector<int>
#define SZ(x) ((int)((x).size()))
#define fi first
#define se second
#define wez(n) int (n); scanf("%d",&(n));
#define wez2(n,m) int (n),(m); scanf("%d %d",&(n),&(m));
#define wez3(n,m,k) int (n),(m),(k); scanf("%d %d %d",&(n),&(m),&(k));
inline void pisz(int n) { printf("%d\n",n); }
template<typename T,typename TT> ostream& operator<<(ostream &s,pair<T,TT> t) {return s<<"("<<t.first<<","<<t.second<<")";}
template<typename T> ostream& operator<<(ostream &s,vector<T> t){FOR(i,SZ(t))s<<t[i]<<" ";return s; }
#define DBG(vari) cerr<<#vari<<" = "<<(vari)<<endl;
#define ALL(t) t.begin(),t.end()
#define FOREACH(i,t) for (__typeof(t.begin()) i=t.begin(); i!=t.end(); i++)
#define TESTS wez(testow)while(testow--)
#define REP(i,a,b) for(int (i)=(a);(i)<=(b);++i)
#define REPD(i,a,b) for(int (i)=(a); (i)>=(b);--i)
#define REMAX(a,b) (a)=max((a),(b));
#define REMIN(a,b) (a)=min((a),(b));
#define IOS ios_base::sync_with_stdio(0);

const int max_size=100000;
char buf[max_size];
int buf_size=0,pos=0;

#define getbuf() buf_size=fread(buf,1,max_size,stdin)
#define get(tok) {if (pos>=buf_size) { if (feof(stdin)) tok=0;	else { getbuf();pos=0; tok=buf[pos++];}}else tok=buf[pos++];}
#define in(v) {int tok;get(tok);while (tok==' ' || tok=='\n')get(tok);v=tok-'0';get(tok);while(tok>='0' && tok<='9'){v*=10;v+=(tok-'0');get(tok);}}

#define N 2005
int leftEnd[N], rightEnd[N], bIG[N], eIG[N];
//const int D = 0; // zmienic przed submitem

void remove (int i, int j) {
   //if (D) { assert(rightEnd[i] == j); assert(leftEnd[j] == i); }
   rightEnd[i] = 0;
   leftEnd[j] = 0;
}

void add (int i, int j) {
   if (rightEnd[i] != 0) {
      const int b = rightEnd[i];
      //if (D) assert(b != j);
      if (b > j) {
         remove(i,b);
         add(j+1,b);
         add(i,j);
      } else { // b < j
         add(b+1,j);
      }
   } else if (leftEnd[j] != 0) {
      const int a = leftEnd[j];
      //if (D) assert(a != i);
      if (a > i) {
         add(i,a-1);
      } else { // a < i
         remove(a,j);
         add(a,i-1);
         add(i,j);
      }
   } else {
      rightEnd[i] = j;
      leftEnd[j] = i;
   }
}


int main () {
   int n;
   in(n);
   vector<pair<int,pii> > sorter;
   REP(i,1,n) REP(j,i,n) {
      int cij;
      in(cij);
      sorter.pb(mp(cij,mp(i,j)));
   }
   sort(ALL(sorter));
   ll cost = 0;
   
   FOREACH(it,sorter) {
      int I = it->se.fi, J = it->se.se;
      if (bIG[I] == eIG[J] && bIG[I] != 0) {
         // lz - skip
      } else {
         // lnz
         add(I,J);
         cost += it->fi;
         
         // wylicz bIG i eIG
         REP(i,1,n) bIG[i] = 0;
         REP(i,1,n) eIG[i] = 0;
         
         int nextId = 1;
         REP(i,1,n) if (rightEnd[i] != 0) {
            int groupId;
            if (0 != eIG[i-1]) {
               groupId = eIG[i-1];
            } else {
               groupId = nextId;
               ++nextId;
            }
            bIG[i] = groupId;
            eIG[rightEnd[i]] = groupId;
         }
      }
   }
   cout << cost;
}