Draw the polygons by using the mouse. Choose colors by clicking on the designed color pane

#include<iostream>
#include<GL/glut.h>
#include<math.h>
#define w 500
#define h 500

using namespace std;
float a[30][2];
int k=0;

void myMouse(GLint button,GLint state,GLint x,GLint y)
{

if(state==GLUT_DOWN)
{
if(button==GLUT_LEFT_BUTTON)
{
a[k][0]=(float)(x-250);
a[k][1]=(float)(250-y);

glBegin(GL_POINTS);
glVertex2f(a[k][0],a[k][1]);
glEnd();
k++;
glFlush();
}
if(button==GLUT_RIGHT_BUTTON)
{
glBegin(GL_LINE_LOOP);
for(int i=0;i<k;i++)
{
glVertex2f(a[i][0],a[i][1]);
}
glEnd();
k=0;
glFlush();

}
}
}
void menu(GLint item)
{
if(item==1)
{
       glColor3f(1.0,0.0,0.0);
       glutMouseFunc(myMouse);
}
if(item==2)
{
glColor3f(0.0,1.0,0.0);
glutMouseFunc(myMouse);
}
if(item==3)
{
glColor3f(0.0,0.0,1.0);
glutMouseFunc(myMouse);
}
if(item==4)
{
glColor3f(0.0,1.0,1.0);
glutMouseFunc(myMouse);
}

}


void myInit()
{
glClearColor(1.0,1.0,1.0,0.0);
glColor3f(0.0f,0.0f,0.0f);
glMatrixMode(GL_PROJECTION);
glPointSize(5);
glLoadIdentity();
gluOrtho2D(-w/2,w/2,-h/2,h/2);
glClear(GL_COLOR_BUFFER_BIT);

}
int main(int argc,char **argv)
{
glutInit(&argc,argv);
glutInitDisplayMode(GLUT_SINGLE|GLUT_RGB);
glutInitWindowSize(500,500);
glutCreateWindow("POLYGON(First Middle Click->Then LEft Clicks->Then Right Clicks)");
myInit();

    glutCreateMenu(menu);
    glutAddMenuEntry("RED",1);
    glutAddMenuEntry("GREEN",2);
    glutAddMenuEntry("BLUE",3);
    glutAddMenuEntry("CYAN",4);
    glutAttachMenu(GLUT_MIDDLE_BUTTON);
    glutMainLoop();

}