Помогите, каждый раз выдает ошибку

#import "chernovikAppDelegate.h"
 
@implementation chernovikAppDelegate
 
@synthesize window;
 
- (void)applicationDidFinishLaunching:(NSNotification *)aNotification
{
    // Insert code here to initialize your application
}
 
@end

#import <Foundation/Foundation.h>
float circleArea(float theRadius); // [44.4]
float rectangleArea(float width, float height); // [44.5]
int main (int argc, const char * argv[]) // [44.7]
{
  NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];
  int pictureWidth;
  float pictureHeight, pictureSurfaceArea,
    circleRadius, circleSurfaceArea;
  pictureWidth = 8;
  pictureHeight = 4.5;
  circleRadius = 5.0;
  pictureSurfaceArea = pictureWidth * pictureHeight;
  circleSurfaceArea = circleArea(circleRadius);
  NSLog(@"Площадь картинки: %f. Площадь окружности: %10.2f.",
    pictureSurfaceArea, circleSurfaceArea);
  [pool drain];
  return 0;
}
float circleArea(float theRadius) // [44.24]
{
  float theArea;
  theArea = 3.14159 * theRadius * theRadius;
  return theArea;
}
float rectangleArea(float width, float height) // [44.31]
{
  return width *height;
}