5. Дипломы

import java.io.*;
import java.math.BigInteger;
import java.util.*;

public class Main {
    public static BigInteger max(BigInteger x, BigInteger y) {
        return x.compareTo(y) > 0 ? x : y;
    }

    public static void main(String args[]) {
        try (PrintWriter out = new PrintWriter(System.out);) {
            Scanner in = new Scanner(System.in);

            BigInteger w = in.nextBigInteger();
            BigInteger h = in.nextBigInteger();
            BigInteger n = in.nextBigInteger();
            BigInteger two = new BigInteger("2");

            BigInteger l = BigInteger.ONE;
            BigInteger r = n.multiply(max(w, h));
            BigInteger x = w.multiply(h).multiply(n);

            while (l.compareTo(r) < 0) {
                BigInteger m = l.add(r).divide(two);

                BigInteger width = m.divide(w);
                BigInteger height = m.divide(h);
                BigInteger num = width.multiply(height);

                if (m.multiply(m).compareTo(x) < 0 || num.compareTo(n) < 0)
                    l = m.add(BigInteger.ONE);
                else
                    r = m;
            }

            out.print(r.toString());
        } catch(Exception e) {
            System.out.println("Exception: " + e);
        }
    }
}