fr.cpp

#include <iostream>
#include <vector>
#include <map>
 
using namespace std;
 
class CNode
{
public:
	vector< CNode*> nexts;
	int prize;
 
	CNode ( int p )
		: prize( p ) {}
 
	void insert ( CNode * toInsert )
	{
		nexts.push_back( toInsert );
	}
 
	int getCount ( void )
	{
		int len = nexts.size(), sum = 0;
 
		if ( len == 0 ) {
			return prize;
		}
 
		for ( int i = 0; i < len; i++ ) {
			sum += nexts[ i ]->getCount();
		}
 
		return prize > sum ? sum : prize;
	}
};
 
int main ( void )
{
	int N, C;
 
	while ( cin >> N >> C ) {
		map<int, CNode* > nodes;
 
		nodes[ C ] = new CNode ( 10000 );
 
		int U, V, W;	
		for ( int i = 0; i < N - 1; i++ ) {
			cin >> U >> V >> W;
 
			if ( nodes.find(U) == nodes.end() ) {
				int tmp = U;
				U = V;
				V = tmp;			
			}
 
			CNode * n = new CNode ( W );
			nodes[ U ] -> insert( n );
			nodes[ V ] = n;
		}
 
		cout << nodes[ C ]->getCount() << endl;
	}
 
	return 0;
}