#include<bits/stdc++.h> using namespace std; int main() { int n,i,a[100],b,s=0; double s1=0; cin>>n; for (i=0;i<n;i++) { cin>>a[i]; } cin>>b; for (i=0;i<n;i++) { if (a[i]==b) s++; } s1=s*1.0/n; cout<<fixed<<setprecision(2)<<s1<<endl; return 0; }

#include<bits/stdc++.h>
using namespace std;
int main(){
	int n,i,a[100],x,s=0;
	double s1=0;
	cin>>n;
	for (i=0;i<n;i++) {
		cin>>a[i];
	}
	cin>>x;
	for (i=0;i<n;i++) {
		if (a[i]==x) {
			s++;
		}
	}
	s1=s*1.0/n;
	cout<<fixed<<setprecision(2)<<s1<<endl;

	return 0;
}