#include <bits/stdc++.h> using namespace std; bool hw(int x){ int sum = 0; int a = x; while(x){ sum = sum * 10 + x % 10; x / 10; } return a == sum; } bool have7(int x){ while(x){ if(x % 10 == 7){ return 1; } x /= 10; } return 0; } int main(){ int n, m, cnt = 0; cin >> n >> m; for(int i = n; i <= m; i++){ if(hw(i) && have7(i)){ cnt++; } } cout << cnt; return 0; }