package main import "fmt" func gcd(a, b int) int { if b > 0 { return gcd(b, a % b) } else { return a } } func main() { fmt.Println("Hello World") const N int = 1000 var A [N]int for i := 0; i < N; i++ { A[i] = i } ans := 0 for i := 0; i < N; i++ { for j := 0; j < N; j++ { ans += gcd(A[i], A[j]) } } fmt.Println(ans) }