#include <bits/stdc++.h>
#define ull unsigned long long
 
using namespace std;
 
ull a, b, ile = 0;
 
bool prim(ull x) {
	for (ull i = 2; i * i <= x; i ++)
		if (x % i == 0)
			return 0;
	return 1;
}
 
void rekDokl(ull x) {
	if (x > b or !prim(x))
		return;
	if (prim(x) and x >= a)
		ile ++;

	rekDokl(x * 10 + 1);
	rekDokl(x * 10 + 3);
	rekDokl(x * 10 + 7);
	rekDokl(x * 10 + 9);
}
 
int main() {
	ios_base::sync_with_stdio(0);
	cin.tie(0); cout.tie(0);
	cin >> a >> b;
 
	rekDokl(2);
	rekDokl(3);
	rekDokl(5);
	rekDokl(7);
 
	cout << ile;
}

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MSAxMDAwMDAwMDAwMDAwMDAwMDAw

1 1000000000000000000