#include <bits/stdc++.h>   using namespace std;   long long g(long long n, long long m) {     long long ans = 0;     for (long long x = 1; x <= n; x++) {       long long minY = 5 - (x % 5);       if (minY <= m) ans += (m - minY) / 5 + 1;     }     return ans;   }   long long gs(long long n, long long m) {     long long ans = 0;     for (long long x = 1; x <= n; x++) {       for (long long y = 1; y <= m; y++) {         if ((x + y) % 5 == 0) ans++;       }     }     return ans;   }   int main() {     ios_base::sync_with_stdio(false);     long long n, m;     cin >> n >> m;     cout << g(n, m) << endl;     return 0;   }   