# ZeroJudge - g470: 12869: Zeroes
### 題目連結：https://zerojudge.tw/ShowProblem?problemid=g470
###### tags: `ZeroJudge` `數學`

#include <iostream>
using namespace std;

static const auto Initialize = [] {
	cin.sync_with_stdio(false); cin.tie(nullptr);
	return nullptr;
}();

int main() {
	long long lower, upper;
	while (cin >> lower >> upper, lower || upper)
		cout << (upper / 5) - (lower / 5) + 1 << '\n';
}