#include <bits/stdc++.h>
using namespace std;
double PI = 2 * acos(0);
std::vector<int> vi;
long long n, m;
int main(int argc, char const *argv[]) {
  cin >> n >> m;
  long long n1, n2, n3, n4, n0;
  long long m1, m2, m3, m4, m0;
  n1 = (n - 1 < 0) ? 0 : (n - 1) / 5 + 1;
  n2 = (n - 2 < 0) ? 0 : (n - 2) / 5 + 1;
  n3 = (n - 3 < 0) ? 0 : (n - 3) / 5 + 1;
  n4 = (n - 4 < 0) ? 0 : (n - 4) / 5 + 1;
  n0 = (n - 5 < 0) ? 0 : (n - 5) / 5 + 1;
  m1 = (m - 1 < 0) ? 0 : (m - 1) / 5 + 1;
  m2 = (m - 2 < 0) ? 0 : (m - 2) / 5 + 1;
  m3 = (m - 3 < 0) ? 0 : (m - 3) / 5 + 1;
  m4 = (m - 4 < 0) ? 0 : (m - 4) / 5 + 1;
  m0 = (m - 5 < 0) ? 0 : (m - 5) / 5 + 1;
  cout << n1 * m4 + n2 * m3 + n3 * m2 + n4 * m1 + n0 * m0;
  return 0;
}
