Code Signal: Intro=40/60

def longestDigitsPrefix(inputString):
    MAKE = []
    TEMP = list(inputString)
    if TEMP[0].isdigit() == True:
        for i in range(len(TEMP)):
            if TEMP[i].isdigit() == True:                
                MAKE.append(TEMP[i])
            else:
                return ''.join(MAKE)
    else:
        return ""
    return ''.join(MAKE)