#include <bits/stdc++.h>
using namespace std;
int main(){
	for(int i=100000;i<1000000;i++){
		if(i/10+700000==4*i&&i%10==7){
			cout<<i;
			return 0;
		}
	}
	return 0;
}

/**************************************************************
	Problem: 1013
	User: zhouhongyi
	Language: C++
	Result: Accepted
	Time:4 ms
	Memory:2072 kb
****************************************************************/