想知道为什么下面代码报UKE：

#include "testlib.h"

int main(int argc,char *argv[]){
	registerTestlib(argc,argv);
	std::string in=ans.readToken();
	std::string out=ouf.readToken();
	if(in=="Yes"){
		int a=0,b=0,c=0;
		for(int i=0;i<3;i++)
			if(out[i]=='Y'|| out[i]=='y')a++;
			else if(out[i]=='E'|| out[i]=='e')b++;
			else c++;
		if(a==1 && b==1 && c==1)
			quitf(_ok,"Hope '%s', get' %s', you got full marks.",in.c_str(),out.c_str());
		else 
			quitf(_wa,"Wrong Answer!");
	}
	else{
		int a=0,b=0;
		for(int i=1;i<3;i++){
			if(out[i]=='N' || out[i]=='n')a++;
			else b++;
		}
		if(a==1 && b==1){
			quitf(_ok,"Hope '%s', get' %s', you got full marks.",in.c_str(),out.c_str());
		}else
			quitf(_wa,"Wrong Answer!");
	}
}