whats wrong?

What is wrong with this code

Code:

#include <GL/gl.h>
#include "aux.h"

int main(int argc, char** argv)
{
    auxInitDisplayMode (AUX_SINGLE | AUX_RGBA);
    auxInitPosition (0, 0, 500, 500);
    auxInitWindow (argv[0]);

    glClearColor (0.0, 0.0, 0.0, 0.0);
    glClear(GL_COLOR_BUFFER_BIT);
    glColor3f(1.0, 1.0, 1.0);
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    glOrtho(-1.0, 1.0, -1.0, 1.0, -1.0, 1.0);
    glBegin(GL_POLYGON);
            glVertex2f(-0.5, -0.5);
            glVertex2f(-0.5, 0.5);
            glVertex2f(0.5, 0.5);
            glVertex2f(0.5, -0.5);
    glEnd();
    glFlush();

    sleep(10);
}

"return" is missing and it is an "int"
-----------------
Engineer223

I know the return was missing, it still no matter what I do says that there are three errors

Perhaps if you could post what the errors were, or point out the lines there on, we might could help. Otherwise I dont know what could be said about that code.