#include <iostream>
using namespace std;
int main() {
    for (int a = 10000; a <= 99999; ++a) {
        int N = 10 * a + 7;
        int newN = 700000 + a;
        if (newN == 4 * N) {
            cout << N << endl;
            break;
        }
    }
    return 0;
}
/**************************************************************
	Problem: 1013
	User: wuweimo
	Language: C++
	Result: Accepted
	Time:3 ms
	Memory:2072 kb
****************************************************************/