Update ex14_05.cpp
Update ex14_05.cpp

Add input check.
heamon7/CppPrimer,at86/CppPrimer,FingerSport/CppPrimer,shuidong/CppPrimer,shuidong/CppPrimer,akanezorap/CppPrimer,zhangzhizhongz3/CppPrimer,FingerSport/CppPrimer,cheng668/CppPrimer,Milk-SF/CppPrimer,lawlietye/CppPrimer,cseryp/CppPrimer,lawlietye/CppPrimer,sheldon66/CppPrimer,pezy/CppPrimer,jwave/CppPrimer,Sublele/CppPrimer,wgs111/CppPrimer,floristt/CppPrimer,heamon7/CppPrimer,jwave/CppPrimer,Milk-SF/CppPrimer,pezy/CppPrimer,sheldon66/CppPrimer,zhangzhizhongz3/CppPrimer,vzyw/CppPrimer,wgs111/CppPrimer,cheng668/CppPrimer,m0000re/CppPrimer,laohei889/CppPrimer,cseryp/CppPrimer,m0000re/CppPrimer,at86/CppPrimer,floristt/CppPrimer,vzyw/CppPrimer,akanezorap/CppPrimer,laohei889/CppPrimer,Sublele/CppPrimer