PAT-B 1010. 一元多项式求导

测试点2,4 考察导函数为0的情况，此时应输出0 0 (真坑)

代码：

#include <iostream>

using namespace std;

int main()
{
int n, m;
bool first = true;

while (cin >> n >> m)
{
if (m != 0) // or n*m != 0
{
if (first)
{
cout << n*m << " " << m-1;
first = false;
} else
{
cout << " " << n*m << " " << m-1;
}
}
}
if (first == true)
{
cout << "0 0";
}

return 0;
}