#include<bits/stdc++.h> using namespace std; bool is_palindrome(int num) { int original = num; int reversed = 0; while (num > 0) { reversed = reversed * 10 + num % 10; num /= 10; } return original == reversed; } bool contains_seven(int num) { while (num > 0) { if (num % 10 == 7) { return true; } num /= 10; } return false; } int main() { int a, b; cin >> a >> b; int count = 0; for (int num = a; num <= b; num++) { if (is_palindrome(num) && contains_seven(num)) { count++; } } cout << count << endl; return 0; }