diff --git a/e-dostavka.user.js b/e-dostavka.user.js
new file mode 100644
index 0000000..bae6feb
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+++ b/e-dostavka.user.js
@@ -0,0 +1,79 @@
+// ==UserScript==
+// @name         [e-dostavka.by, gipermall.by] price comparison
+// @namespace    http://tampermonkey.net/
+// @version      2
+// @description  Show prices per kilo, compare between sites
+// @author       nomoreknights
+// @match        https://e-dostavka.by/*
+// @match        https://gipermall.by/*
+// @grant        unsafeWindow
+// @grant        GM.xmlHttpRequest
+// @require      https://cdnjs.cloudflare.com/ajax/libs/arrive/2.4.1/arrive.min.js
+// @require      https://cdnjs.cloudflare.com/ajax/libs/ramda/0.26.1/ramda.min.js
+// @require      https://unpkg.com/ohm-js@0.14.0/dist/ohm.min.js
+// ==/UserScript==
+
+(function () {
+    'use strict';
+    const price = (() => {
+        const float = n => parseFloat(n.sourceString)
+        const priceG = ohm.grammar(`Price { Price = digit+ "р." digit+ "к." Price? }`)
+        const priceS = priceG.createSemantics().addOperation('val', {
+            Price: (rub, _2, kop, _4, _5) => float(rub) * 100 + float(kop),
+        })
+        const weightG = ohm.grammar(`Weight {
+            Exp       = BS* AnyWeight BS* AnyWeight? BS*
+            AnyWeight = MulWeight | Weight
+            Weight    = float (OneUnit | ThUnit)
+            OneUnit   = Dot<"г">  | Dot<"мл"> | Dot<"шт"> | Dot<"см">
+            ThUnit    = Dot<"кг"> | Dot<"л"> | Dot<"м">
+            Dot<R>    = R "."*
+            MulWeight = float ("x" | "х" | "*") Weight
+            BS        = ~AnyWeight any
+            float = (digit digit* "." digit) -- fl
+            	| digit+
+            }`)
+        const weightS = weightG.createSemantics().addOperation('val', {
+            Exp: (_, weight, __, ___, _____) => weight.val(),
+            Weight: (n, u) => float(n) * u.val(),
+            OneUnit: _ => 1, ThUnit: _ => 1000,
+            MulWeight: (d, _, w) => float(d) * w.val(),
+        })
+        const interpret = (g, s) => (text) => s(g.match(text))
+        return (price, weight) => (interpret(priceG, priceS)(price).val() / interpret(weightG, weightS)(weight).val() / 100 * 1000)
+    })()
+    const $ = unsafeWindow.jQuery; // somehow, when @including jquery, infinite scroll stops working.
+    const template = $("<a/>").css({
+        'background-color': '#fbba00',
+        'color': 'black', // default is #cb4f2b
+        'padding': '2px',
+        'border-radius': '5px',
+        'font-size': '14px',
+        'font-family': 'MyriadProCondencedBoldItalic',
+        'position': 'absolute',
+        'right': '5px'
+    }).attr('target', '_blank')
+    $(document).arrive(".products_card", { existing: true }, div => {
+        const normalizedPrice = price(
+            $(div).find('div > form > div.prices__wrapper > div > div.prices_block > div > div.price').text(),
+            $(div).find('a.fancy_ajax').text()
+        )
+         const button = template.clone()
+         const url = (R.test(/e-dostavka/, location.host) ? R.identity : R.flip)(R.replace)('e-dostavka', 'gipermall', $(div).find('a.fancy_ajax').attr('href'))
+         $(div).find('a.fa').replaceWith(button)
+         button.text(normalizedPrice.toFixed(2))
+         GM.xmlHttpRequest({
+             method: 'GET', url, onload: page => {
+                 try {
+                     const html = $($.parseHTML(page.responseText))
+                     const competingPrice = price(
+                         html.find('div.services_wrap:nth-child(3) > div:nth-child(1) > div:nth-child(1) > div:nth-child(1)').text(),
+                         html.find('.template_1_columns > h1:nth-child(2)').text()
+                     )
+                     const difference = Math.abs(1 - competingPrice / normalizedPrice) * 100
+                     button.text((i, _) => `${_} (${competingPrice >= normalizedPrice ? '>' : '<'}${difference.toFixed(0)}%)`).prop('href', url)
+                 } catch (e) { }
+             }
+         });
+    });
+})();
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