include stdio include math int main int argc const char argv int nScan

#include <stdio.h>
#include <math.h>

int main (int argc, const char * argv[]) {
	int				nScanned;
	int				n;
	double			sumX, sumY;
	double			sumX2, sumY2;
	double			sumXY;
	
	n = 0;
    sumX = sumY = sumX2 = sumY2 = sumXY = 0.0;
	do {
		double		x, y;
		nScanned = scanf("%lg %lg", &x, &y);
		if (nScanned == 2) {
			n++;
			sumX += x;
			sumX2 += x * x;
			sumY += y;
			sumY2 += y * y;
			sumXY += x * y;
		}
	} while (nScanned == 2);
	
	double			slope, intercept;
	slope = (n * sumXY - sumX * sumY)
	/ (n * sumX2 - sumX * sumX);
	intercept = (sumY - slope * sumX) / n;
	
	double			correlation;
	correlation = slope * sqrt((n * sumX2 - sumX * sumX)
							   / (n * sumY2 - sumY * sumY));
	
	printf("%g\t%g\t%g\n", slope, intercept, correlation);
	return 0;
}