package main

import "flag"

var sumMax *int = flag.Int("max", 1000, "max value to sum to"); 

var sumMethod *int = flag.Int("method", 0, "sum method");

func Between(a, b int) chan int {
	c := make(chan int, 1000);
	go func() {
		for a <= b {
			c <- a;
			a += 1;
		}
		close(c);
	}();
	return c;
}

func ChanSum(max int) int {
    sum := 0;
	for i := range Between(0, *sumMax) {
		sum += i
	}
    return sum;
}

func LoopSum(max int) int {
    sum := 0;
    i := 0;
	for i <= max {
		sum += i;
        i += 1;
	}
    return sum;
}


func main() {
    flag.Parse();
    var sum int;
    var max int = *sumMax;
    if *sumMethod == 1 {
        sum = LoopSum(max);
    } else {
        sum = ChanSum(max);
    }
    println("Sum is", sum);
}