#include<bits/stdc++.h> using namespace std; int main() { int n; cin >> n; int c = 0; int a[10]; for (int i = 0; i < n; i++) { cin >> a[i]; } for (int i = 0; i < n; i++) { if (a[i] <= 18) { c = c + 1; } } printf("%.2f", c * 100.0 / n); cout << "%" << endl; return 0; }