#include <bits/stdc++.h>   using namespace std;   const double pi = 3.14159265358979323846;   void rw() {}   int main() {     ios_base::sync_with_stdio(0);     cin.tie(0);     cout.tie(0);     vector<long long> s;     long long n, c, f, se;     cin >> n;     s.push_back(4);     s.push_back(7);     for (int i = 0; i < s.size(); i++) {       f = 0, se = 0;       c = s[i];       while (c) {         if (c % 10 == 4)           f++;         else           se++;         c /= 10;       }       if (s[i] >= n && f == se) {         cout << s[i] <<   n ;         break;       } else {         s.push_back(s[i] * 10 + 4);         s.push_back(s[i] * 10 + 7);       }     }     return 0;   }   