#2. 視頻推薦 Video Recommendation

當今的視頻網站大多有視頻推送功能。在推送的頁面上，出現的視頻的順序由用戶常看的視頻類型和每一個視頻的“評分”決定。視頻的“評分”往往與點贊數、點踩數、播放量、完播率、評論數等有關。

在本題中，我們採用一種簡單的“評分”計算方法，即 “評分” = 點贊數 - 點踩數 。

現有 個人在觀看某一視頻後留下了評價，每個人的評價為點贊（用 表示）或點踩（用 表示），求該視頻的“評分”。

Today, most social media platforms will recommend videos to users. On the page having that function, videos appear in a certain order, according to both the user preference and the ratings of videos. The rating of a video is related to likes, dislikes, finish rate and comments. In this problem, we adopt a simplified approach to calculate the rating of a video, that is, rating = likes - dislikes .

There are people leaving a comment after watching a video, which is either a like or a dislike. You are asked to calculate the rating of this video.

第一行一个整数 。

接下来 行，每行一个字符串，为 “” 或 “” 之一，表示观众留下的评价。

第一行一個整數 。

接下來 行，每行一個字符串，為 “” 或 “” 之一，表示觀眾留下的評價。

The first line of the input contains an integer .

In the following lines, each line contains a string, which is either or , representing the comment left by an audience.

一个整数，表示视频的“评分”。

一個整數，表示視頻的“評分”。

Write an integer in one line, representing the rating of the video.

Sample 1 input

5
dislike
dislike
dislike
like
dislike

Sample 1 output

-3

对于全部测试数据，满足 。

對於全部測試數據，滿足 。

For all test data, .