int n,i,m[100],x;
	float s=0.0;
	cin>>n;
	for(i=0;i<n;i++){
		cin>>m[i];
	} 
	cin>>x;
	for(i=0;i<n;i++){
		if(x==m[i]){
			s++;
		}
	}
	printf("%.2f",s/n);
	return 0;
}

/**************************************************************
	Problem: 1354
	User: zzz
	Language: C++
	Result: Compile Error
****************************************************************/