CF152A.Marks

Vasya, or Mr. Vasily Petrov is a dean of a department in a local university. After the winter exams he got his hands on a group's gradebook.

Overall the group has n students. They received marks for m subjects. Each student got a mark from 1 to 9 (inclusive) for each subject.

Let's consider a student the best at some subject, if there is no student who got a higher mark for this subject. Let's consider a student successful, if there exists a subject he is the best at.

Your task is to find the number of successful students in the group.

瓦西里（即瓦西里·彼得罗夫先生）是一所本地大学某院系的系主任。冬季考试结束后，他拿到了一个班级的成绩册。

该班级共有 $n$ 名学生，每名学生在 $m$ 门科目中均获得了一个介于 $1$ 到 $9$（含）之间的分数。

我们称一名学生在某门科目中“最优秀”，当且仅当没有任何其他学生在该科目中获得比他更高的分数。我们称一名学生为“成功学生”，当且仅当存在至少一门科目，他在该科目中是最优秀的学生。

你的任务是求出该班级中成功学生的数量。

The first input line contains two integers n and m (1 ≤ n, m ≤ 100) — the number of students and the number of subjects, correspondingly. Next n lines each containing m characters describe the gradebook. Each character in the gradebook is a number from 1 to 9. Note that the marks in a rows are not sepatated by spaces.

第一行输入包含两个整数 $n$ 和 $m$（$1 \leq n, m \leq 100$），分别表示学生人数和科目数。接下来的 $n$ 行，每行包含 $m$ 个字符，描述成绩表。成绩表中的每个字符均为 $1$ 到 $9$ 之间的数字。注意：同一行中的各成绩之间不以空格分隔。

Print the single number — the number of successful students in the given group.

输出单个数字——给定组中成功学生的数量。

In the first sample test the student number 1 is the best at subjects 1 and 3, student 2 is the best at subjects 1 and 2, but student 3 isn't the best at any subject.

In the second sample test each student is the best at at least one subject.

在第一个样例测试中，学生 1 在科目 1 和科目 3 上表现最佳，学生 2 在科目 1 和科目 2 上表现最佳，但学生 3 在任何科目上均未表现最佳。

在第二个样例测试中，每位学生至少在一科上表现最佳。