此代码为何CE?

#include<bits/stdc++.h>
using namespace std;
int a,b,chen_zhe,noip=1;
char kkksc03;//出镜率太低了
int main(){
    while(cin>>a>>kkksc03>>b){
        chen_zhe=a*noip+b*chen_zhe;
        noip*=b;
        int QQhongbao=gcd(chen_zhe,noip); 
		chen_zhe/=QQhongbao;
		noip/=QQhongbao;
    }
	if(chen_zhe<0&&noip<0){chen_zhe=abs(chen_zhe);noip=abs(noip);}
    else if(chen_zhe>0&&noip<0){noip=abs(noip);cout<<"-";}
	else if(chen_zhe<0&&noip>0){chen_zhe=abs(chen_zhe);cout<<"-";}
	if(chen_zhe==0) cout<<"0";
	else if(noip==1) cout<<chen_zhe; 
	else cout<<chen_zhe<<"/"<<noip;
    return 0;
}