#include <bits/stdc++.h>
using namespace std;
#define int long long
using ll=long long;
using vi=vector<int>;
using pii=pair<int,int>;
#define ALL(c) begin(c),end(c)
#define RALL(c) rbegin(c),rend(c)
#define ITR(i,b,e) for(auto i=(b);i!=(e);++i)
#define FORE(x,c) for(auto &x:c)
#define REPF(i,a,n) for(int i=a,i##len=(int)(n);i<i##len;++i)
#define REP(i,n) REPF(i,0,n)
#define REPR(i,n) for(int i=(int)(n);i>=0;--i)
#define SZ(c) ((int)c.size())
#define CONTAIN(c,x) (c.find(x)!=end(c))
#define OUTOFRANGE(y,x,h,w) (y<0||x<0||y>=h||x>=w)
#define dump(...)
const int DX[9]={0,1,0,-1,1,1,-1,-1,0},DY[9]={-1,0,1,0,-1,1,1,-1,0};
#define INF (1001001001)
#define INFLL (1001001001001001001ll)
template<class T> ostream& operator << (ostream &os,const vector<T> &v) {
    ITR(i,begin(v),end(v)) os<<*i<<(i==end(v)-1?"":"\n"); return os; }
template<class T> istream& operator >> (istream &is,vector<T> &v) {
    ITR(i,begin(v),end(v)) is>>*i; return is; }
template<class T> istream& operator >> (istream &is, pair<T,T> &p) {
    is>>p.first>>p.second; return is; }
template<class T> bool chmax(T &a,const T &b) {if(a<b) {a=b;return 1;} return 0;}
template<class T> bool chmin(T &a,const T &b) {if(b<a) {a=b;return 1;} return 0;}
template <class T> using heap = priority_queue<T,vector<T>,greater<T>>;
//------------------------------------------------------------------------------
struct before_main_function {
    before_main_function() {
        #ifdef int
            #undef INF
            #define INF INFLL
            #define stoi stoll
        #endif
        cin.tie(0);ios::sync_with_stdio(false);
        cout<<setprecision(15)<<fixed;
        #define endl "\n"
    }
} before_main_function;
//------------------8<------------------------------------8<--------------------

struct union_find {
    vector<int> data;
    union_find(int size) : data(size, -1) { }
    void unite(int x, int y) {
        x = root(x); y = root(y);
        if(x != y) {
            if(data[y] < data[x]) swap(x, y);
            data[x] += data[y];
            data[y] = x;
        }
    }
    bool same(int x, int y) {
        return root(x) == root(y);
    }
    int root(int x) {
        return data[x] < 0 ? x : data[x] = root(data[x]);
    }
    int size(int x) {
        return -data[root(x)];
    }
};
signed main() {
    int n;
    cin>>n;
    vector<vector<int>> A(n,vector<int>(n));
    cin>>A;

    union_find uf(n);
    int ans=0;
    heap<pair<int,pii>> hp;
    REP(i,n) {
        REPF(j,i+1,n) {
            hp.push({A[i][j],{i,j}});
        }
    }
    vector<vector<pii>> g(n);
    while(!hp.empty()) {
        int c=hp.top().first;
        pii e=hp.top().second; hp.pop();

        heap<pii> q;
        vector<int> d(n,INF);
        d[e.first]=0;
        q.push({0,e.first});
        while(!q.empty()) {
            int v=q.top().second; q.pop();
            FORE(x,g[v]) {
                if(d[x.first]>d[v]+x.second) {
                    d[x.first]=d[v]+x.second;
                    q.push({d[x.first],x.first});
                }
            }
        }
        if(uf.same(e.first,e.second)) {
            if(d[e.second]<c) {
                cout<<-1<<endl;
                return 0;
            }
            if(d[e.second]==c) continue;
        }

        ans+=c;
        uf.unite(e.first,e.second);
        g[e.first].push_back({e.second,c});
        g[e.second].push_back({e.first,c});
    }
    cout<<ans<<endl;
    return 0;
}


Measured memory_bytes: 2680