func main()
	var a: int :: cui@inputInt()
	var b: int :: cui@inputInt()
	var c: int :: cui@inputInt()
	
	var flag: bool :: false
	if(c <= b)
		if(c % a = 0)
			do cui@print("\{c / a}\n")
			do flag :: true
		end if
	end if
	block
		var x: int :: c + b
		if(x % a = 0)
			do cui@print("\{x / a}\n")
			do flag :: true
		end if
	end block
	if(!flag)
		do cui@print("-1\n")
	end if
end func