import re

def check_equation(file_path):
    pattern = r'^\s*(x|[1-9]\d*)\s*[\+\-\*\/]\s*(x|[1-9]\d*)\s*=\s*(x|[1-9]\d*)\s*$'

    with open(file_path, 'r', encoding='utf-8') as file:
        for line in file:
            line = line.strip()
            if re.match(pattern, line):
                if line.count('x') == 1:
                    print('yes')
                else:
                    print('no')
            else:
                print('no')

file_path = 'TaskE16/test.in'
check_equation(file_path)