Опсег

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.util.StringTokenizer;

public class Range{

   static long zbirCifri(long x) {
        long zbir=0;
        while(x!=0) {
            zbir+=x%10;
            x/=10;
        }
        return zbir;
    }

    static long proveri(long N, long A, long B) {
        // Vasiot kod tuka
        if(A==B) return -1;
        //System.out.println(A);
        //System.out.println(B);

        if(A*A + zbirCifri(A) + 200*A == N) {
            return A;
        }
        if(B*B + zbirCifri(B) + 200*B == N) {
            return B;
        }

        long mid=(B+A)/2;

        long shouldBe=mid*mid + zbirCifri(mid) + mid*200;

        if(shouldBe==N) return mid;

        if(N<shouldBe) {
            return proveri(N,A,mid);
        } else return proveri(N,mid,B);

    }

    public static void main(String[] args) throws Exception {
        int i,j,k;

        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

        long N = Long.parseLong(br.readLine());

        StringTokenizer st = new StringTokenizer(br.readLine());
        long A = Long.parseLong(st.nextToken());
        long B = Long.parseLong(st.nextToken());

        long res = proveri(N, A, B);
        System.out.println(res);

        br.close();

    }

}