#include <stdio.h>
int main(void)
{
int n,i;
double yi,xi,a0,a1,no;
double sxi,syi,sxiyi,sxi2;
printf("Input number of data sets, N:\n");
scanf("%d\n",&n);
printf("no=%d\n",n);
printf("Input data sets, as\n");
printf("x1, y1\n");
printf("x2, y2\n");
//printf("...\n");
sxi=0;syi=0;sxi2=0;sxiyi=0;
for(i=0;i<n;i++){
scanf("%lf %lf\n",&xi,&yi);
printf("xi=%lf,yi=%lf\n", xi,yi);
sxi+=xi;
syi+=yi;
sxi2+=xi*xi;
sxiyi+=xi*yi;
}
no=(double) n;
//printf("no=%lf\n",no);
//printf("sxi=%lf\n",sxi);
//printf("syi=%lf\n",syi);
//printf("sxi2=%lf\n",sxi2);
//printf("sxiyi=%lf\n",sxiyi);
//printf("bunbo=%lf\n",no*sxi2-sxi*sxi);
a0=(sxi2*syi-sxiyi*sxi)/(no*sxi2-sxi*sxi);
a1=(no*sxiyi-sxi*syi)/(no*sxi2-sxi*sxi);
printf("y=%lf+%lfx\n",a0,a1);
return 0;
}