#include<iostream> #include<vector> #include<algorithm> #include<functional> #include<queue> #include<stack> #include<set> #include<climits> #include<cstdlib> #include<cmath> #include<string> #include<iomanip> using namespace std; #define INF 1 << 29 #define LL long long int LL const MOD = 1000000007; int main(){ cin.tie(0); ios::sync_with_stdio(false); double n; cin >> n; vector<double> a(n); for(int i = 0; i < n; i++){ cin >> a[i]; } double x = 0.0; double y = 0.0; double xy = 0.0; double xx = 0.0; for(int i = 0; i < n; i++){ x += (double)i; y += a[i]; xy += a[i]*((double)i); xx += ((double)i)*((double)i); } double first = ((xx*y)-(xy*x))/(((double)n)*xx - (x*x) ); double d = ((((double)n)*xy)-(x*y))/(((double)n)*xx - (x*x)); double c = 0.0; for(int i = 0; i < n; i++){ c += (a[i] - (((double)i)*d + first))*(a[i] - (((double)i)*d + first)); } cout << fixed; cout << setprecision(17) << first << " "; cout << setprecision(17) << d << endl; cout << setprecision(17) << c << endl; return 0; }