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#include <iostream>
#include <stdio.h>
#include <iostream>
#include <map>
#include <utility>

using namespace std;

bool debug = true;

void displayBase(bool B[], int n) {
  if (debug) {
    int i = 0;
    int j = 0;
    while (!((j == n) && (i == 0 ))) {
      cout << B[j * n + i] << ' ';
      i++;
      if (i == n) {
        i = 0;
        j++;
        cout << endl;
      };
    };
    cout << endl;
  };
};

void addCol(bool B[], int n,  int addThis, int toThis) {
  int i;
  for (i = 0; i < n; i++) {
    B[toThis * n + i] =  B[toThis * n + i] ^ B[addThis * n + i];
  };
};

void swapCols(bool B[], int n, int x, int y) {
  for (int i = 0; i < n; i++) {
    B[x * n + i] =  B[x * n + i] ^ B[y * n + i];
    B[y * n + i] =  B[x * n + i] ^ B[y * n + i];
    B[x * n + i] =  B[x * n + i] ^ B[y * n + i];
  };
};


void cycleInto(bool B[], int n, int what, int where) {
  for (int i = what - 1; i >= where; i-- ) {
    swapCols(B, n, i, i+1);
  };
};

bool gaussianReduce(bool B[], int n, int upTo, int onePos) {
  // cout << " clearing base up to  " << upTo << endl;
  // displayBase(B, n);
  while ( onePos < n && !B[upTo * n + onePos])
    onePos++;
  // cout << " one pos is " << onePos << endl;
  if (onePos == n)
    return false;
  int j = 0;
  int i = 0;
  while (j < onePos) {
    if (B[ i * n + j]) 
      i++;
    j++;
  };
  // cout << " i: " << i << " j:  " << j <<   endl << endl;
  if ((i == upTo) and (j == onePos )) {
    return true;
  } else if ((B[ i * n + j])) {
    addCol(B, n, i, upTo );
    return gaussianReduce(B, n, upTo, onePos);
  } else {
    cycleInto(B, n, upTo, i);
    // cout << "cycled into " << endl;
    // displayBase(B, n);
    return true;
  };
  return false;
};

// bool gaussianReduce(bool B[], int n, int upTo) {
//   int i;
//   int nowReducingRow = 0;
//   int currentCol = 0;
//   bool foundOne;
//   while (nowReducingRow <= upTo and currentCol < n) {
//     i = nowReducingRow;
//     foundOne = false;
//     while ( !foundOne && i <= upTo ) {
//       if ( B[i * n + currentCol] )
//         foundOne = true;
//       else
//         i++;
//     };
//     if (foundOne) {
//       if (i != nowReducingRow) {
//         swapCols(B, n, i, nowReducingRow);
//         // if (debug) cout << "current Col is " << currentCol <<
//         //   " swapping cols " << i << " and " << nowReducingRow << endl;
//         // displayBase(B, n);
//       };
//       for (i = nowReducingRow + 1; i <= upTo; i++) {
//         if ( B[i * n + currentCol] ) {
//           addCol(B, n, nowReducingRow, i);
//           // if (debug) cout << "current Col is " << currentCol <<
//           //    " adding col " << nowReducingRow << " to " << i << endl;
//           // displayBase(B, n);
//         };
//       };
//       nowReducingRow++;
//     };
//     currentCol++;
//   };
//   bool resu = false;
//   for (i = 0; i < n; i++) {
//     resu = resu || B[upTo*n + i];
//   };
//   // if (resu) {
//   //   if (debug) cout << "Dobra macierz" << endl;
//   // } else
//   //   if (debug) cout << "ZUAAA macierz" << endl;
//   return resu;
// };

void makeBase(bool B[], int n) {
  int i = 0; int j = 0;
  while (!((j == n) && (i == 0))) {
    B[j * n + i] = 0;
    i++;
    if (i == n) {
      i = 0; j++;
    }; }; };

void addToBase(bool B[], int n, int whichCol, int from, int to) {
  for (int i = 0; i < n; i++) 
    B[whichCol * n + i ] = (i >= from) && (i <= to); };

void debugPrint(long C[], int n) {
  if (debug) {
    int i = 0;
    int j = 0;
    while (!((j == n) && (i == 0 ))) {
      cout << C[j * n + i] << ' ';
      i++;
      if (i == n) {
        i = 0;
        j++;
        cout << endl;
      };
    };
    cout << endl;
  };
};

void findSmallest(long C[], int n, int &x, int &y, int &val) {
  x = 0;
  y = 0;
  val = -1;
  for (int i = 0; i < n; i++) {
    for (int j = 0; j < n; j++) {
      if (i <= j) {
        if ((val == -1) and not(C[i * n + j] == 0)) {
          val = C[i * n + j];
          x = i;
          y = j;
        };
        if (C[i * n + j] < val and not(C[i * n + j] == 0)) {
          val = C[i * n + j];
          x = i;
          y = j;
        };
      };
    };
  };
};

int main() {
  bool kurrent;
  int n;
  cin >> n;
  bool B[n * n];
  makeBase(B, n);
  long c;

  multimap<long, pair<int, int> > m;

  // read C
  for (int i = 0; i < n; i++) {
    for (int j = 0; j < n; j++) {
      if (i <= j) {
        scanf(" %ld", &c);
        m.insert(pair<long, pair<int, int> >(c, pair<int, int>(i,j)));
      };
    };
  };

  // cout << "Number of elements with key a: " << m.count("a") << endl;
  //
  //
  int i = 1234;
  int j = 56789;
  int cVal = 123121;
  int noInBase = 0;
  long long baseCost = 0;

  for (multimap<long, pair<int, int> >::iterator it = m.begin();
       ((noInBase < n) && (it != m.end()) );
       ++it)
   {
    // if (debug) cout << "  [ val: " << (*it).first 
    //      << ", from : " << (*it).second.first
    //      << ", to : " << (*it).second.second << "]" << endl;
     addToBase(B, n, noInBase, (*it).second.first, (*it).second.second);
     if (gaussianReduce(B, n, noInBase, 0)) {
       // displayBase(B, n);
       noInBase++;
       baseCost += (*it).first;
     };
   }
  cout << baseCost;
};