package main

import "fmt"
import "math"

func squareRoot(value int) (float64, error) {
	if value >= 0 {
		return math.Sqrt(float64(value)), nil
	} else {
		return 0, fmt.Errorf("invalid input: %v", value)
	}
}

func sumRoots(v1, v2 int) (float64, error) {
	a, err := squareRoot(v1)
	if err != nil {
		return 0, err
	}
	b, err := squareRoot(v2)
	if err != nil {
		return 0, err
	}

	return a + b, nil
}

func main() {
	if sum, err := sumRoots(4, 16); err == nil {
		fmt.Printf("The sum is %v\n", sum)
		return
	} else {
		fmt.Println("Value cannot be negative")
	}
}