我用的eclipse编译的C++，我在project下运行完一个文件，在运行另一个，总是出现下面的问题：提示红色括号出错！
如果重新建立一个文件夹，则可以运行。
求大神指教！！！！！

#include <iostream>
const double litre=0.264179;   //1公升=0.264179加仑
double ave(double n_litre,double distance);
int main()
{
    using namespace std;
    double a1,b1,c1,a2,b2,c2;
    char d;
    do
    {
        cout << "input two car's litre of oil:" <<endl;
        cin >> a1,a2;
        cout << "input two car's distance:" <<endl;
        cin >> b1,b2;
        c1=ave(a1,b1);
        c2=ave(a2,b2);
        cout.setf(ios::fixed);
        cout.setf(ios::showpoint);
        cout.precision(2);
        cout <<c1<<endl;
        cout <<c2<<endl;
        if(c1>c2)
            cout << "the first car is good." << endl;
        else if(c1==c2)
            cout << "the two car has the same level."<<endl;
        else if(c1<c2)
            cout << "the second car is good." << endl;
        cout << "if you want comulate another input 'y';"
            " end of program intput 'n'."<<endl;
        cin >> d;
    }while((d=='y')||(d=='Y'));
    cout << "end."<<endl;
    return 0;
}
double ave(double n_litre,double distrance)
{
    return(distrance/(litre*n_litre));
}