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#include <iostream>
#include <vector>
#include <set>
#include <map>
#include <algorithm>
#include <cmath>
#include <ctime>
#include <cstdlib>
#include <cstdio>
#include <utility>
#include <iomanip>
#include <assert.h>
#define MP make_pair
#define PB push_back
#define FOR(i, a, b) for(int i =(a); i <=(b); ++i)
#define RE(i, n) FOR(i, 1, n)
#define FORD(i, a, b) for(int i = (a); i >= (b); --i)
#define REP(i, n) for(int i = 0;i <(n); ++i)
#define VAR(v, i) __typeof(i) v=(i)
#define FORE(i, c) for(VAR(i, (c).begin()); i != (c).end(); ++i)
#define ALL(x) (x).begin(), (x).end()
#define SZ(x) ((int)(x).size())
#define PB push_back
#define MP make_pair
#ifdef LOCAL
#define debug(x) {cerr <<#x <<" = " <<x <<"\n"; }
#define debugv(x) {{cerr <<#x <<" = "; FORE(itt, (x)) cerr <<*itt <<", "; cerr <<"\n"; }}
#else
#define debug(x)
#define debugv(x)
#endif
#define make(type, x) type x; cin>>x;
#define make2(type, x, y) type x, y; cin>>x>>y;
#define make3(type, x, y, z) type x, y, z; cin>>x>>y>>z;
using namespace std;
typedef long long ll;
typedef long double LD;
typedef pair<int, int> PII;
typedef pair<ll, ll> PLL;
typedef vector<int> VI;
typedef vector<ll> VLL;
typedef vector<pair<int, int> > VPII;
typedef vector<pair<ll, ll> > VPLL;

template<class C> void mini(C&a4, C b4){a4=min(a4, b4); }
template<class C> void maxi(C&a4, C b4){a4=max(a4, b4); }
template<class T1, class T2>
ostream& operator<< (ostream &out, pair<T1, T2> pair) { return out << "(" << pair.first << ", " << pair.second << ")";}
const int N = 1e6;
int rep[N];
int Find(int v) {
  if (rep[v] == v) {
    return v;
  } else {
    rep[v] = Find(rep[v]);
    return rep[v];
  }
}
int size[N];
int Union(int a, int b) {
  a = Find(a);
  b = Find(b);
  if (a == b) {
    return 0;
  }
  if (size[a] < size[b]) {
    swap(a, b);
  }
  rep[b] = a;
  size[a] += size[b];
  return 1;
}
int main() {
  // nie zapomnij o ll
  ios_base::sync_with_stdio(0);
  cout << fixed << setprecision(10);
  // int beg = 1.0 * clock() / CLOCKS_PER_SEC;
  
  
  make(int, n);
  n++;
  vector<pair<int, pair<int, int> > > edges;
  RE (i, n) {
    rep[i] = i;
    size[i] = 1;
  }
  RE (i, n) {
    FOR (j, i + 1, n) {
      make(int, c);
      edges.PB(MP(c, MP(i, j)));
    }
  }
  sort(ALL(edges));
  long long res = 0;
  for (auto p : edges) {
    res += p.first * Union(p.second.first, p.second.second);
  }
  cout<<res<<endl;
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  // nie zapomnij o ll
  return 0;
}