expression = input("Enter your numerical expression: ")
expression_split = expression.split(' ')

# Convert numeric things to integers first.
for item in range(len(expression_split)):
    try:
        expression_split[item] = int(expression_split[item])
    except ValueError:
        pass

while len(expression_split) > 1:
    position = None
    sign = None

    # If / or * exist we pick the first available / or *
    for exp in range(len(expression_split)):
        if expression_split[exp] in ['/', '*']:
            position = exp
            sign = expression_split[exp]
            break

    # If no / or * exist.
    if position is None:
        position = 1
        sign = expression_split[1] # First operator (+ or -) available.

    if sign == "+":
        result = expression_split[position-1] + expression_split[position+1]
    elif sign == "-":
        result = expression_split[position-1] - expression_split[position+1]
    elif sign == "*":
        result = expression_split[position-1] * expression_split[position+1]
    elif sign == "/":
        result = expression_split[position-1] / expression_split[position+1]
    else:
        print("Error, invalid operator.")

    expression_split = expression_split[:(position-1)] + [result] + expression_split[(position+2):]

print(expression, "=", expression_split[0])