from decimal import Decimal
#引入decimal模块是因为python不是默认高精浮点数

def main():
    print('==Exercise 6==')
    
    i = input("Input the temperature you like to convert? (e.g., 45F, 102C etc.) :").lower()

    ins = ""
    use_celsius = False

    for ii in i:
        if ii in '1234567890.':
            ins+=ii
        elif ii in 'cf':
            use_celsius = ii == 'c'
            break
        else:
            print(f"Unexcepted char {ii}! Ignored.")
    if len(ins)!=len(i)-1:
        print(f"WARNING! content below \'c\' or \'f\' is ignored! (using {ins} {'c' if use_celsius else 'f'})")
    
    ins = Decimal(ins)
    #c/5 = f-32/9
    #f = c*9/5+32
    #c = (f-32)*5/9
    o = ins*9/5+Decimal(32.0) if use_celsius else (ins-Decimal(32.0))*5/9

    print(f"The temperature in {'Fahrenheit' if use_celsius else 'Celsius'} is {o} degrees.")

    print('==End Of Ex6==')
    return 0

if __name__ == '__main__':
    main()