#include <bits/stdc++.h>
#define int long long int
using namespace std;
signed main(){
set<int> sett;
set<int>::iterator it;
for(int i=2;i<=100;i++){
int bit=1;
string str;
while(bit<=i){
if(i & bit){
str.push_back('4');
}
else{
str.push_back('0');
}
bit=bit<<1;
}
reverse(str.begin(), str.end());
sett.insert(stoi(str));
}
int x;
cin>>x;
for(it=sett.begin();it!=sett.end();it++){
if(*it >= x){
if(*it % x == 0){
cout<<*it<<"\n";
break;
}
}
}
}
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