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//Maciej Poleski
#ifdef DEBUG
#define _GLIBCXX_CONCEPT_CHECKS
#include <iostream>
#include <fstream>
#include <cstdlib>
#include <cassert>
namespace
{
namespace Wrapper
{
std::ifstream in;
std::ofstream out;
}
void init(int argc, char **argv)
{
    if (argc != 3)
    {
        std::cerr << "Potrzeba dokładnie dwóch argumentów\n";
        std::abort();
    }
    Wrapper::in.open(argv[1]);
    Wrapper::out.open(argv[2]);
}
}
#define check(x) assert(x)
#else
#ifndef NDEBUG
#define NDEBUG
#endif
#define check(x)
#include <iostream>
namespace
{
namespace Wrapper
{
std::istream &in = std::cin;
std::ostream &out = std::cout;
}
}
#endif

#include <cstdint>

namespace
{
namespace Wrapper
{
typedef std::uint_fast64_t uint_fast64_t;
typedef std::uint_fast32_t uint_fast32_t;
typedef std::uint_fast16_t uint_fast16_t;
typedef std::uint_fast8_t uint_fast8_t;

typedef std::uint64_t uint64_t;
typedef std::uint32_t uint32_t;
typedef std::uint16_t uint16_t;
typedef std::uint8_t uint8_t;

typedef std::int_fast64_t int_fast64_t;
typedef std::int_fast32_t int_fast32_t;
typedef std::int_fast16_t int_fast16_t;
typedef std::int_fast8_t int_fast8_t;

typedef std::int64_t int64_t;
typedef std::int32_t int32_t;
typedef std::int16_t int16_t;
typedef std::int8_t int8_t;

typedef std::size_t size_t;
}

}

#include <string>
#include <algorithm>
#include <limits>
#include <locale>
#include <cstring>
#include <utility>
#include <cstdlib>
#include <tr1/random>
#include <algorithm>
#include <vector>
#include <stack>
#include <queue>
#include <list>
#include <iomanip>
#include <set>
#include <map>
#include <memory>
#include <functional>
#include <unordered_map>
#include <unordered_set>
#include <complex>

namespace
{
using namespace Wrapper;

struct Info
{
    uint_fast16_t begin,end;
    uint_fast32_t price;
};

static bool operator<(const Info& lhs,const Info& rhs)
{
    return lhs.price<rhs.price;
}

constexpr uint_fast32_t maxN=2000;

static std::uint_least32_t price[maxN][maxN];
static int_fast16_t *basis;

static inline bool isZero(const Info& info)
{
    return info.begin>info.end;
}

static bool tryInterval(Info& info)
{
    while(!isZero(info))
    {
        if(basis[info.begin]==-1)
        {
            basis[info.begin]=info.end;
            return true;
        }
        else
        {
            auto basisEnd=basis[info.begin];
            if(basisEnd<=info.end)
                info.begin=basisEnd+1;
            else
            {
                info.begin=info.end+1;
                info.end=basisEnd;
            }
        }
    }
    return false;
}

inline static void solution()
{
    using std::swap;
    std::uint_fast32_t n;
    in >> n;
    Info *info=new Info[n*(n+1)/2];
    Info *ptr=info;
    for(uint_fast32_t i=0;i<n;++i)
    {
        for(auto j=i;j<n;++j)
        {
            in>>price[i][j];
            ptr->begin=i;
            ptr->end=j;
            ptr->price=price[i][j];
            ++ptr;
        }
    }
    basis=new int_fast16_t[n];
    for(size_t i=0;i<n;++i)
        basis[i]=-1;

    std::sort(info,ptr);
    Info* i=info;
    uint_fast64_t result=0;
    for(auto est=n;est>0;++i)
    {
        if(tryInterval(*i))
        {
            --est;
            result+=i->price;
        }
    }
    out<<result<<'\n';
    delete [] basis;
    delete [] info;
}

} // namespace

int main(int argc, char **argv)
{
    std::ios_base::sync_with_stdio(false);
#ifdef DEBUG
    init(argc, argv);
#else
    (void)argc;
    (void)argv;
#endif
    solution();
    return 0;
}