URAL 1551 Sumo Tournament

1551. Sumo Tournament

Time limit: 1.0 second
Memory limit: 64 MB

A sumo tournament is held in Tokyo, in which 2 N sportsmen take part. In each encounter there is a winner, and the loser drops out of the tournament. Thus, in order to determine the winner of the tournament, it is necessary to conduct  N rounds.

The organizers wish that in as many rounds as possible all encounters would be held between sumoists from different prefectures of Japan. For that they can forge the drawing results arbitrarily.

Input

The first line contains the number  N (1 ≤  N ≤ 10). Each of the next 2 N lines contains the name of a sumouist and the prefecture which he presents. The name and prefecture are sequences of Latin letters of length not exceeding 30.

Output

Output the maximal number of rounds in which sumoists from the same prefecture will not fight each other regardless of the outcomes of encounters (that is, find the maximal possible  K such that in at least K rounds all encounters will be between sumoists from different prefectures). The organizers can control the initial arrangement of sportsmen but can't control results of encounters.

Sample

input	output
3 Homasho Ishikawa Tamakasuga Tokyo Futeno Tochigi Takekaze Tokyo Kasugao Yamaguchi Kotoshogiku Ishikawa Kotomitsuki Tokyo Miyabiyama Shizuoka	1

Problem Author: Sergey Pupyrev
Problem Source: The 11th Urals Collegiate Programing Championship, Ekaterinburg, April 21, 2007

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就是一个淘汰赛问题，问在保证来自于同一城市的队伍不遭遇的情况下最多能进行几轮比赛。

今天学了map容器，发现简直神奇，真高兴！！

#include <iostream>
#include <cstdio>
#include <cstring>
#include <string>
#include <map>

using namespace std;

#define FOR(i,s,t) for(int i=s;i<=t;++i)
#define max(x,y) ((x)>(y)?(x):(y))

map<string,int> cnt;
int n,maxv;

int main()
{
	maxv=0;
	cin >> n;
	FOR(i,1,(1<<n))
	{
		string s1,s2;
		cin >> s1 >> s2;
		++cnt[s2];
		maxv=max(cnt[s2],maxv);
	}
	for (int i=0;i<=30;++i)
		if ((1<<i)>=maxv) {cout << n-i << endl;break;}
	return 0;
}