public class Naloga2 {

    public static void main(String[] args) {

        String a = "123";
        String b = "456";
        // os(a, b);
        System.out.println(dv((a), (b)));
        // System.out.println(stOut("0"));
    }

    static void os(String a, String b) {
        String result = "";
        for (int i = 0; i < b.length(); i++) {
            String s = "";
            int c = 0;
            int v1 = b.charAt(i) - '0';
            for (int j = a.length() - 1; j >= 0; j--) {
                int v2 = a.charAt(j) - '0';
                int product = v1 * v2 + c;
                s = (j > 0) ? (product) % 10 + s : product + s;
                c = product / 10;
            }
            System.out.println((s.charAt(0) == '0') ? 0 : s);
            if (i == 0) {
                result = s;
            } else {
                result += 0;
                while (s.length() != result.length()) {
                    s = 0 + s;
                }
                result = sumStr(result, s);
            }
        }
        for (int i = 0; i < result.length(); i++) {
            System.out.print("-");
        }
        System.out.println();
        System.out.println(result);
    }

    static String sumStr(String a, String b) {
        String result = "";
        int c = 0;
        if (a.length() > b.length()) {
            while (a.length() != b.length()) {
                b = 0 + b;
            }
        } else if (b.length() > a.length()) {
            while (a.length() != b.length()) {
                a = 0 + a;
            }
        }
        for (int i = a.length() - 1; i >= 0; i--) {
            int v1 = b.charAt(i) - '0';
            int v2 = a.charAt(i) - '0';
            int sum = v1 + v2 + c;
            int x = (i > 0) ? sum % 10 : sum;
            result = x + result;
            c = sum / 10;
        }
        return result;
    }

    static String [] sodaDolzinaEnaka(String a, String b) {
        while(a.length()%2!=0){
            a=0+a;
        }
        while(b.length()%2!=0){
            b=0+b;
        }
        if (a.length() > b.length()) {
            while (a.length() != b.length()) {
                b = 0 + b;
            }
        } else if (b.length() > a.length()) {
            while (a.length() != b.length()) {
                a = 0 + a;
            }
        }
        return new String[]{a,b};
    }

    static String stOut(String s) {
        int i = 0;
        if (isZero(s)) {
            return "0";
        }
        while (i < s.length() && s.charAt(i) == '0') {
            i++;
        }
        return s.substring(i, s.length());
    }

    static boolean isZero(String str) {
        for (int i = 0; i < str.length(); i++) {
            if (str.charAt(i) != '0')
                return false;
        }
        return true;
    }

    static int numZer(String s) {
        int c = 0;
        int i = 0;
        while(i<s.length() && s.charAt(i)=='0') {
            c++;
            i++;
        }
        return c;
    }

    static String dv(String a, String b) {
        System.out.println(a + " " + b);

        if (isZero(a) || isZero(b)) {
            return "0";
        }

        if (stOut(a).length() == 1 || stOut(b).length() == 1) {
            return linMnoz(a, b);
        }
        String arr[] = sodaDolzinaEnaka(a, b);
        String tmpa = arr[0];
        String tmpb = arr[1];
        String a0 = stOut(tmpa.substring(tmpa.length() / 2, tmpa.length()));
        String b0 = stOut(tmpb.substring(tmpb.length() / 2, tmpb.length()));
        String a1 = stOut(tmpa.substring(0, tmpa.length() / 2));
        String b1 = stOut(tmpb.substring(0, tmpb.length() / 2));


        String a0b0 = dv(a0, b0);

        System.out.println(a0b0);

        String a0b1 = dv(a0, b1);

        System.out.println(stOut(a0b1));

        String a1b0 = dv(a1, b0);

        System.out.println(stOut(a1b0));

        String a1b1 = dv(a1, b1);

        System.out.println(stOut(a1b1));

        String str = tmpa + tmpb;
        int n = str.length() / 2;

        for (int i = 0; i < n; i++) {
            a1b1 += 0;
        }
        String sum = sumStr(a0b1, a1b0);
        for (int i = 0; i < n / 2; i++) {
            sum += 0;
        }

        String r1 = sumStr(a1b1, sum);
        String r2 = sumStr(r1, a0b0);

        return stOut(r2);
    }

    static String linMnoz(String a, String b) {
        String result = "";
        for (int i = 0; i < b.length(); i++) {
            String s = "";
            int c = 0;
            int v1 = b.charAt(i) - '0';
            for (int j = a.length() - 1; j >= 0; j--) {
                int v2 = a.charAt(j) - '0';
                int product = v1 * v2 + c;
                s = (j > 0) ? (product) % 10 + s : product + s;
                c = product / 10;
            }
            if (i == 0) {
                result = s;
            } else {
                result += 0;
                while (s.length() != result.length()) {
                    s = 0 + s;
                }
                result = sumStr(result, s);
            }
        }
        return result;
    }

    static String ka(String a, String b) {
        return "";
    }

}