#include <iostream>
#include <vector>
#include <string>
#include <sstream>

using namespace std;

class MafiaGame {
public:
	double probabilityToLose(int N, vector <int> decisions) {
		int cnt[500];
		memset(cnt, 0, sizeof(cnt));
		for(int i=0;i<decisions.size();i++) cnt[decisions[i]]++;
		int m = 0;
		for(int i=0;i<N;i++) m = max(m, cnt[i]);
		if(m==1) return 0.0;
		int c = 0;
		for(int i=0;i<N;i++) if(m==cnt[i]) c++;
		double res = 1.0/c;
		if(c==1) return 1.0;
		while(c!=1){
			int rest = N-c*m;
			if(rest%c==0) return 0.0;
			c = rest%c;
		}
		return res;
	}
};