#include <bits/stdc++.h>
using namespace std;
int n, k;
long long a[205];
int er[205], wu[205];
int dp[205][6005];
void prin() {
  for (int t = 0; t <= 4; t++) {
    for (int j = 0; j <= k; j++) {
      if (t == 0 && j == k - 1) cout << "(";
      cout << dp[j][t] << " ";
      if (t == 0 && j == k - 1) cout << ") ";
    }
    cout << endl;
  }
}
int main() {
  memset(dp, -1, sizeof(dp));
  cin >> n >> k;
  for (int i = 0; i < n; i++) {
    cin >> a[i];
    long long t = a[i];
    while (t % 5 == 0) wu[i]++, t /= 5;
    t = a[i];
    while (t % 2 == 0) er[i]++, t /= 2;
  }
  dp[0][0] = 0;
  int ans = -1;
  for (int i = 0; i < n; i++) {
    for (int t = 6000; t >= wu[i]; t--) {
      for (int j = k; j >= 1; j--) {
        if (dp[j - 1][t - wu[i]] != -1)
          dp[j][t] = max(dp[j][t], dp[j - 1][t - wu[i]] + er[i]);
        if (j == k && dp[j][t] != -1) ans = max(ans, min(t, dp[j][t]));
      }
    }
  }
  cout << ans;
  return 0;
}
