a=1 b='x' c=2 if (type(a) == int or type(a) == float) and (b in ['+','-','x','/']): if (type(c) == int or type(c) == float): if b=='+': result = a + c if b == '-': result = a - c if b == 'x': result = a * c if b == '/': result = a/c print(result) else: print("input error")