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 Go (1.6) (judge verdict: Accepted)

package main

import (
	"bufio"
	"fmt"
	"os"
	"strconv"
)

func main() {
	sc.Split(bufio.ScanWords)
	a, b := nextInt(), nextInt()
	if a+b == 15 {
		puts("+")
	} else if a*b == 15 {
		puts("*")
	} else {
		puts("x")
	}
	wt.Flush()
}

var (
	sc  = bufio.NewScanner(os.Stdin)
	rdr = bufio.NewReaderSize(os.Stdin, 1000000)
	wt  = bufio.NewWriter(os.Stdout)
)

func next() string {
	sc.Scan()
	return sc.Text()
}

func nextInt() int {
	i, _ := strconv.Atoi(next())
	return i
}

func nextFloat64() float64 {
	f, _ := strconv.ParseFloat(next(), 64)
	return f
}

func nextInts(n int) []int {
	slice := make([]int, n)
	for i := 0; i < n; i++ {
		slice[i] = nextInt()
	}
	return slice
}

func nextFloat64s(n int) []float64 {
	slice := make([]float64, n)
	for i := 0; i < n; i++ {
		slice[i] = nextFloat64()
	}
	return slice
}

func nextMega() string {
	buf := make([]byte, 0, 1000000)
	for {
		l, p, _ := rdr.ReadLine()
		buf = append(buf, l...)
		if !p {
			break
		}
	}
	return string(buf)
}

func putf(format string, a ...interface{}) {
	fmt.Fprintf(wt, format, a...)
}

func puts(a ...interface{}) {
	fmt.Fprintln(wt, a...)
}