#include <iostream>
#include <cmath>
#include <algorithm>
#include <stdio.h>
#include <cstring>
#include <string>
#include <cstdlib>
#include <vector>
#include <bitset>
#include <map>
#include <chrono>
#include <functional>
#include <unordered_set>
#include <unordered_map>
#include <numeric>
#include <queue>
#include <ctime>
#include <stack>
#include <set>
#include <list>
#include <deque>
#include <iomanip>
#include <sstream>
#include <fstream>
#include <stdarg.h>
#include <utility>
using namespace std;
#define pb push_back
#define mp make_pair
#define ll long long
#define ull unisgned long long
#define ld long double
#define all(a) a.begin(), a.end()
#define SORT(a) sort(all(a))
#define pii pair<int, int>
#define tii triple<int, int, int>
#define e 1e-7
#define PI acos(-1)
#define sz(a) (int)(a.size())
#define inf 1e17
#define vi vector<int>
#define F first
#define S second
#define rng(x) for(int _ = 0; _ < (x); _++)
#define rngi(i, x) for(int i = 0; i < (x); i++)
#define rngsi(s, i, x) for(int i = (s); i <(x); i++)
#define problem ""
template<typename A, typename B, typename C>
struct triple{
A X;
B Y;
C Z;
triple(A a = 0, B b = 0, C c = 0) :X(a), Y(b), Z(c) {}
};
template<typename A, typename B, typename C>
triple<A, B, C> make_triple(A a = 0, B b = 0, C c = 0){
return triple<A, B, C>(a, b, c);
}
template<typename A, typename B, typename C>
bool operator<(const triple<A, B, C>& a, const triple<A, B, C>& b){
if (a.X != b.X)
return a.X < b.X;
if (a.Y != b.Y)
return a.Y < b.Y;
return a.Z < b.Z;
}
template<typename T, typename SS>
ostream& operator<<(ostream& ofs, const pair<T, SS>& p){
ofs << "( " << p.F << " , " << p.S << " )";
return ofs;
}
template<typename T>
void print(T a){
for (auto i : a)
cout << i << ' ';
cout << '\n';
}
template<typename T>
T max(T a, T b, T c){
return max(a, max(b, c));
}
template<typename T>
T min(T a, T b, T c){
return min(a, min(b, c));
}
template<typename T, typename D>
D min(T a){
return *min_element(all(a));
}
template<typename T, typename D>
D max(T a){
return *max_element(all(a));
}
struct custom_hash{
static uint64_t splitmix64(uint64_t x){
x += 0x9e3779b97f4a7c15;
x = (x ^ (x >> 30)) * 0xbf58476d1ce4e5b9;
x = (x ^ (x >> 27)) * 0x94d049bb133111eb;
return x ^ (x >> 31);
}
size_t operator()(uint64_t x) const{
static const uint64_t FIXED_RANDOM = chrono::steady_clock::now().time_since_epoch().count();
return splitmix64(x + FIXED_RANDOM);
}
};/*
static int _N;
static int _dist[110][110];
static int _quota, _user_query;
void _ini_query(int N, int k) {
int ret;
_N = N;
for (int i = 0; i < _N; i++)
for (int j = 0; j < _N; j++) {
ret = scanf("%d", &_dist[i][j]);
assert(ret == 1);
}
if (k == 1 || k == 3) _quota = _N * (_N - 1) / 2;
else if (k == 2 || k == 4 || k == 6) _quota = (7 * _N + 1) / 2;
else _quota = 5 * _N;
_user_query = 0;
}
int getDistance(int i, int j) {
_user_query++;
if (_user_query > _quota) {
printf("0\n");
exit(0);
}
if (i < 0 || i >= _N) return 0;
if (j < 0 || j >= _N) return 0;
return _dist[i][j];
}*/
#include "towns.h"
int hubDistance(int n, int sub) {
vector<vi> dd(n, vi(n, -1));
auto get = [&](int x, int y){
if(x == y)return 0;
if(dd[x][y] >= 0) return dd[x][y];
return dd[x][y]=dd[y][x]= getDistance(x, y);
};
vi d1(n);
rngi(i, n - 1) d1[i + 1] = get(0, i + 1);
int q = 1;
int vv = max<vi, int>(d1);
rngi(j, n - 1) if(d1[j] > d1[q]) q = j;
vi d2(n);
rngi(i, n) d2[i] = get(q, i);
int ans = max<vi, int>(d2);
int res = 1e9;
vector<int> poss;
rngi(i, n){
int a = (d2[i] + vv - d1[i]) / 2;
int b = vv - a;
if(max({a, b, ans - a}) < res) {
res = max({a, b, ans - a});
poss.clear();
poss.push_back(a);
} else if(max({a, b, ans - a}) == res)
poss.push_back(a);
//~ cout << i << " " << res << endl;
}
return res;
}
/*
int main() {
FILE *f;
f = freopen("towns.in","r",stdin);
assert(f != NULL);
//f = freopen("towns.out","w",stdout);
assert(f != NULL);
int ncase, R, N;
int subtask;
int ret;
ret = scanf("%d%d",&subtask,&ncase);
assert(ret == 2);
for (int i = 0; i < ncase; i++) {
ret = scanf("%d",&N);
assert(ret == 1);
_ini_query(N,subtask);
R=hubDistance(N,subtask);
printf("%d\n",R);
}
return 0;
}
//
*/
