#include<cmath>
#include<vector>
#include<iostream>

using namespace std;

class cash_flow {
private:
		vector<double> times;
		vector<double> amounts;
		

public:
		cash_flow();
		cash_flow(istream&);
		vector<double> get_times();
		vector<double> get_amounts();
		double principal_value_discrete(const double &r);
		double principal_value_cont(const double &r);
		double IRR();
};