#include using namespace std; typedef long long ll; typedef pair< int, int > pii; typedef vector< int > vi; typedef vector< vi > vvi; typedef vector< ll > vl; typedef vector< vl > vvl; typedef vector< pii > vp; typedef vector< vp > vvp; typedef vector< string > vs; typedef vector< double > vd; typedef vector< vd > vvd; template< class T1, class T2 > int upmin( T1 &x, T2 v ){ if( x > v ){ x = v; return 1; } return 0; } template< class T1, class T2 > int upmax( T1 &x, T2 v ){ if( x < v ){ x = v; return 1; } return 0; } const int INF = 0x3f3f3f3f; int N; vi X, Y; void init(){ cin >> N; X = Y = vi( N ); for( int i = 0; i < N; ++i ) cin >> X[ i ] >> Y[ i ]; } struct dsu{ vi fa; dsu( int sz ){ fa = vi( sz ); for( int i = 0; i < sz; ++i ) fa[ i ] = i; } int find( int x ){ return fa[ x ] == x ? x : fa[ x ] = find( fa[ x ] ); } int merge( int a, int b ){ int x = find( a ); int y = find( b ); if( x == y ) return 0; fa[ x ] = y; return 1; } }; map< int, vi > group; int eu_dis2( int a, int b, int x, int y ){ int dx = a - x; int dy = b - y; return dx * dx + dy * dy; } double eu_dis( int a, int b, int x, int y ){ double dx = a - x; double dy = b - y; return sqrt( dx * dx + dy * dy ); } void preprocess(){ dsu *uf = new dsu( N ); for( int i = 0; i < N; ++i ) for( int j = i + 1; j < N; ++j ) if( eu_dis2( X[ i ], Y[ i ], X[ j ], Y[ j ] ) <= 100 ) uf->merge( i, j ); for( int i = 0; i < N; ++i ) group[ uf->find( i ) ].emplace_back( i ); } void solve(){ double ans = 1.0; for( auto it = group.begin(); it != group.end(); ++it ){ for( int i = 0; i < it->second.size(); ++i ) for( int j = i + 1; j < it->second.size(); ++j ) upmax( ans, 2.0 + eu_dis( X[ ( it->second )[ i ] ], Y[ ( it->second )[ i ] ], X[ ( it->second )[ j ] ], Y[ ( it->second )[ j ] ] ) ); } cout << fixed << setprecision( 8 ) << ans << endl; } signed main(){ ios::sync_with_stdio( 0 ); init(); preprocess(); solve(); return 0; }