n = int(input())
sum = 0
ls = list(map(int, input().split()))
for i in range(0,n):
sum += ls[i]
ls.sort()
avg = sum/n
ans = 0
if(avg >= 4.5):
print(0)
else:
for i in range(0,n):
if(avg >= 4.5):
break
else:
sum += (5- ls[i])
ls[i] = 5
avg = sum/n
ans+=1
print(ans)
#include <iostream>
#include "vector"
#include "cmath"
#include "iomanip"
#include "string"
#include "list"
#include "algorithm"
#include "set"
#include "map"
#include "numeric"
using namespace std;
long long mod = 1e9 + 7;
#define ll long long
#define ld long double
#define s set<int>
#define pair pair<int,int>
const int SIZE = 1e6+1;
const ld e = 1e-12;
int convert(long long n) {
int dec = 0, i = 0, rem;
while (n!=0) {
rem = n % 10;
n /= 10;
dec += rem * pow(2, i);
++i;
}
return dec;
}
ll gcd(ll a, ll b)
{
if (a * b == 0) return a + b;
if (a < b)
return gcd(a,b%a);
else
return gcd(a%b,b);
}
void fastio()
{
cin.tie(0);
ios_base::sync_with_stdio(false);
}
ll fact(ll a)
{
ll sum = 1;
for (int i = 2; i <= a; i++)
{
sum *= i;
}
return sum;
}
int qpow(int a,int b) {
int r = 1;
while (b) {
if (b & 1)r = r % mod * a % mod;
a = a % mod * a % mod;
b >>= 1;
}
return r;
}
bool comp(pair a, pair b)
{
return (a.first < b.first);
}
int main() {
fastio();
int n;
cin >> n;
vector<ld>a(n);
ld sum = 0;
for (int i = 0; i < n; i++) {
cin >> a[i];
sum += a[i];
}
int count = 0;
sort(a.begin(),a.end());
for (int i = 0; i < n; i++) {
if (sum / n >= 4.5) {
break;
}
if (a[i] != 5.0) {
sum += fabs(a[i] - 5.0);
count++;
}
// cout << sum / n << '\n';
}
cout << count << " ";
}
305B - Continued Fractions | 1165B - Polycarp Training |
1646C - Factorials and Powers of Two | 596A - Wilbur and Swimming Pool |
1462B - Last Year's Substring | 1608B - Build the Permutation |
1505A - Is it rated - 2 | 169A - Chores |
765A - Neverending competitions | 1303A - Erasing Zeroes |
1005B - Delete from the Left | 94A - Restoring Password |
1529B - Sifid and Strange Subsequences | 1455C - Ping-pong |
1644C - Increase Subarray Sums | 1433A - Boring Apartments |
1428B - Belted Rooms | 519B - A and B and Compilation Errors |
1152B - Neko Performs Cat Furrier Transform | 1411A - In-game Chat |
119A - Epic Game | 703A - Mishka and Game |
1504C - Balance the Bits | 988A - Diverse Team |
1312B - Bogosort | 1616B - Mirror in the String |
1660C - Get an Even String | 489B - BerSU Ball |
977C - Less or Equal | 1505C - Fibonacci Words |