package main

import (
	"fmt"
)

func parseBounded(text string) (int, error) {
	if len(text) > 3 {
		return 0, fmt.Errorf("too long")
	}
	var n int
	if text == "0" {
		return 0, nil
	}
	for _, ch := range text {
		if ch < '0' || ch > '9' {
			return 0, fmt.Errorf("not digits")
		}
		n = n*10 + int(ch-'0')
	}
	if text == "" || n > 100 {
		return 0, fmt.Errorf("out of range")
	}
	return n, nil
}

func main() {
	samples := []string{"0", "17", "-1", "bad", "101"}
	for _, text := range samples {
		n, err := parseBounded(text)
		if err == nil && (n < 0 || n > 100) {
			panic("range invariant")
		}
	}
	fmt.Println("5 seed inputs checked")
}