#include <iostream>
#include <utility>
#include <vector>
#include <cmath>
#include <algorithm>
using namespace std;

#define gcu getchar_unlocked
#define pcu putchar_unlocked
#define _il inline
#define _in _il int in
#define _sc _il bool scan
_in(int c){int n=0;bool m=false;if(c=='-')m=true,c=gcu();
	do{n=10*n+(c-'0'),c=gcu();}while(c>='0');return m?-n:n;} //&&c<='9'
_in() {return in(gcu());}
_sc(int &n){int c=gcu();return c==EOF?false:(n=in(c),true);}
_sc(char &c){c=gcu();gcu();return c!=EOF;}
//_sc(string &s){int c;s="";
//	for(;;){c=gcu();if(c=='\n'||c==' ')return true;else if(c==EOF)return false;s+=c;}}
template <typename H,typename... T> _sc(H &h, T&&... t){return scan(h)&&scan(t...);}
#define _vo _il void out
#define _vl _il void outl
template <typename T>
_vo(T n){static char buf[20];char *p=buf;
	if(n<0)pcu('-'),n*=-1;if(!n)*p++='0';else while(n)*p++=n%10+'0',n/=10;
	while (p!=buf)pcu(*--p);}
_vo(const char *s){while(*s)pcu(*s++);}
_vo(char c){pcu(c);}
//_vo(string &s){for (char c: s) pcu(c);}
template <typename H,typename... T> _vo(H&& h, T&&... t){out(h);out(move(t)...);}
//template <typename T> _vo(vector<T> &v){for(T &x:v)out(&x == &v[0]?"":" "),out(x);out('\n');}
_vl(){out('\n');}
template <typename... T> _vl(T&&... t){out(move(t)...);outl();}

template<int N>
struct sieve {
	bool s[N];
	constexpr sieve() : s() {
		for (int i = 0; i < N; i++)
			s[i] = true;
		for (int i = 4; i < N; i += 2)
			s[i] = false;
		for (int i = 9; i < N; i += 6)
			s[i] = false;
		for (int i = 6, e = sqrt(N); i <= e; i += 6) {
			for (int j : {i - 1, i + 1})
				if (s[j])
					for (int k = j * j; k < N; k += j)
						s[k] = false;
		}
	}
};

template<int N>
struct twin {
	int t[N/10], l;
	constexpr twin() : t(), l(1) {
		sieve<N> s;
		t[0] = 5;
		for (int i = 0; i < N; i++)
			if (s.s[i - 2] && s.s[i])
				t[l++] = i;
	}
};

int main() {
	enum {N = 10001};
	twin<N> t;
	for (int n; (n = in());) {
		auto r = upper_bound(t.t, t.t + t.l, n) - 1;
		outl(*r - 2, ' ', *r);
	}
}

#include <cstdio>
#include <vector>
#include <algorithm>
#include <queue>

using namespace std;

template <class T>
using gp_queue=priority_queue<T, vector<T>, less<T>>;

using Weight=int;
using DArray=vector<Weight>;
using DMatrix=vector<DArray>;

static const Weight INF=1<<29;

struct Edge {
    size_t src, dst;
    Weight weight;
    Edge() {}
    Edge(size_t src, size_t dst, Weight weight=1):
        src(src), dst(dst), weight(weight)
    {}
};

bool operator<(const Edge &e, const Edge &f) {
    if (e.weight != f.weight) {
        return e.weight > f.weight;
    } else {
        return e.src!=f.src? e.src<f.src : e.dst<f.dst;
    }
}

using Edges=vector<Edge>;
using Vertex=vector<Edge>;
using Graph=vector<Vertex>;

void join(Graph &g, size_t s, size_t d, Weight w=1) {
    // non-directed
    g[s].push_back(Edge(s, d, w));
    g[d].push_back(Edge(d, s, w));
}

void connect(Graph &g, size_t s, size_t d, Weight w=1) {
    // directed
    g[s].push_back(Edge(s, d, w));
}

pair<Weight, Edges> minimum_spanning_tree(const Graph &g, size_t s=0) {
    /* Prim */
    size_t V=g.size();
    Edges T;
    Weight total=0;

    vector<bool> visited(V);
    gp_queue<Edge> q; q.push(Edge(-1, s, 0));
    while (!q.empty()) {
        Edge e=q.top(); q.pop();
        if (visited[e.dst]) continue;

        T.push_back(e);
        total += e.weight;
        visited[e.dst] = true;
        for (const Edge &f: g[e.dst])
            if (!visited[f.dst])
                q.push(f);
    }

    return make_pair(total, T);
}

int main() {
    size_t n;
    scanf("%zu", &n);

    Graph g(n);
    for (size_t i=0; i<n; ++i)
        for (size_t j=0; j<n; ++j) {
            Weight a;
            scanf("%d", &a);

            if (a > -1)
                connect(g, i, j, a);
        }

    printf("%d\n", minimum_spanning_tree(g).first);
    return 0;
}