你题目理解错了
底下是我写的
#include<iostream>
#include<utility>
using namespace std;
#define pi 3.14
#define up 50
void main()
{   
	int N;
    cin>>N;
	pair<double,double> a;
	int i=1;
	while(cin>>a.first>>a.second)
	{
		double sum(0);
		int count(0);
		while(sum<(pi*(a.first*a.first+a.second*a.second)/2))
		{   
			sum+=up;
			count++;
        }
		cout<<"Property "<<i<<": "<<"This property will begin eroding in year "<<count<<"."<<endl;
		i++;	
	}
	cout<<"END OF OUTPUT."<<endl;
}