#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, k, ans = 0;
  cin >> n >> k;
  int two[n], five[n];
  long long a;
  for (int i = 0; i < n; ++i) {
    cin >> a;
    five[i] = two[i] = 0;
    while (a && a % 5 == 0) {
      five[i]++;
      a /= 5;
    }
    while (a && a % 2 == 0) {
      two[i]++;
      a /= 2;
    }
  }
  int dp[2][n + 1][5200];
  for (int i = 0; i < 2; ++i) {
    for (int j = 0; j <= n; ++j) {
      for (int k = 0; k < 5200; ++k) {
        dp[i][j][k] = -20001;
      }
    }
  }
  for (int num_take = 1; num_take <= k; ++num_take) {
    for (int num_available = 1; num_available <= n; ++num_available) {
      for (int pow5 = 0; pow5 < 5200; ++pow5) {
        if (num_take > num_available) {
          dp[num_take % 2][num_available][pow5] = -20001;
          continue;
        }
        dp[num_take % 2][num_available][pow5] =
            max(dp[(num_take + 1) % 2][num_available][pow5],
                dp[num_take % 2][num_available - 1][pow5]);
        if (pow5 - five[num_available - 1] == 0) {
          dp[num_take % 2][num_available][pow5] = max(
              dp[num_take % 2][num_available][pow5], two[num_available - 1]);
        }
        if (pow5 - five[num_available - 1] >= 0) {
          dp[num_take % 2][num_available][pow5] =
              max(dp[num_take % 2][num_available][pow5],
                  dp[(num_take + 1) % 2][num_available - 1]
                    [pow5 - five[num_available - 1]] +
                      two[num_available - 1]);
        }
        ans = max(ans, min(pow5, dp[num_take % 2][num_available][pow5]));
      }
    }
  }
  cout << ans;
}
