Problem:
Score : 100 points

Problem Statement

You are given two integers a and b.
Determine if a+b=15 or a\times b=15 or neither holds.

Note that a+b=15 and a\times b=15 do not hold at the same time.

Constraints

1 \leq a,b \leq 15

All values in input are integers.

Input

Input is given from Standard Input in the following format:

a b

Output

If a+b=15, print +;
if a\times b=15, print *;
if neither holds, print x.

Sample Input 1

4 11

Sample Output 1

+

4+11=15.

Sample Input 2

3 5

Sample Output 2

*

3\times 5=15.

Sample Input 3

1 1

Sample Output 3

x

1+1=2 and 1\times 1=1, neither of which is 15.

Solution in Java (OpenJDK 1.8.0) (judge verdict: Wrong Answer)

import java.math.BigDecimal;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Object o = run();
        if (o != null)
            System.out.println(o);
    }

    static Object run() {
        try (Scanner sc = new Scanner(System.in)) {
            int a = sc.nextInt();
            int b = sc.nextInt();
            if (a * b == 15) return "*";
            if (a + b == 15) return "*";
             return "x";
        }
    }
}

class ChenNumberUtil {
    static Collection<Integer> getDivisors(int n) {
        ArrayList<Integer> al = new ArrayList<>();
        for (int i = 1; i * i <= n; i++) {
            if (n % i == 0) {
                al.add(i);
                if (n / i != i)
                    al.add(n / i);
            }
        }
        Collections.sort(al);
        return al;
    }
}

class ChenBitUtil {
    static int popCount(int bit) {
        return Integer.bitCount(bit);
    }

    static boolean isFlag(int bit, int i) {
        return 0 != (bit & (1 << i));
    }

    static int setTrue(int bit, int i) {
        return bit |= (1 << i);
    }

    static int setFalse(int bit, int i) {
        return bit &= ~(1 << i);
    }

    static int setReverse(int bit, int i) {
        return isFlag(bit, i) ? setFalse(bit, i) : setTrue(bit, i);
    }

    static int reverseAll(int bit) {
        return ~bit;
    }
}