CODE:

#include 
#include 

int main(int argc,char* argv[]) {
	int i;
	double sum;
	int width;
	if(argc<2)width=100;
	else width=atoi(argv[1]);
	for(i=0,sum=0;i<width;i++)sum+=sqrt((double)width*width-(double)i*i);
	printf("%1.15f\n",sum*4/width/width);
	return 0;
}