#ifndef INCLUDE_VEC2
#define INCLUDE_VEC2

#include <vector>
#include <iostream>
using namespace std;

class Vec2{
private:
	double ele[2] ;

public:
	Vec2( double x , double y ) { ele[ 0 ] = x ; ele[ 1 ] = y ;}
	Vec2( ) { ele[ 0 ] = 0 ; ele[ 1 ] = 0 ; }
	Vec2 & operator=( const Vec2 & c ) ;
	Vec2 & operator+=( const Vec2 & c ) ;
	Vec2 & operator-=( const Vec2 & c ) ;
	double get( int i ) const { return ele[ i ] ; } 
	void set( int i , double x ) { ele[ i ] = x ; } 

	Vec2 operator + ( ) const { return *this ; } 
	Vec2 operator + ( Vec2 c ) const ;
	Vec2 operator - ( ) const ;
	Vec2 operator - ( Vec2 c ) const ;
	double abs() const ;
	double norm() const ;
	friend double prod( const Vec2 & , const Vec2 & ) ;
};


std::ostream &operator<<(std::ostream & , const Vec2 & );


#endif