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