#include "iostream"
#include "fstream"
#include "string"
#include "algorithm"
//#include "cmath"

using namespace std;

int ciSta(char el, char arr[]) {
	int len = sizeof(arr)/sizeof(arr[0]);
	for (int j=0;j<len;j++) {
		if (arr[j]==el) return j;
	}
	return -1;
}

int main() {
	ifstream in; in.open("input.txt");
	ofstream out; out.open("output.txt");
	int T, D, countl;
	in >> T >> D;
	string parole[T], parole2[T];
	char lettere[T][26];
	for (int j=0;j<T;j++) {
		in >> parole[j];
	}
	for (int j=0;j<T;j++) {
		parole2[j] = "";
	}
	for (int i=0;i<T;i++) {
		countl = 0;
		string str = parole[i];
		for (int k;k<str.size();k++) {
			if (ciSta(str[k],lettere[i])>=0) {
				parole2[i] = parole2[i]+to_string(ciSta(str[k],lettere[i]));
			}
			else {
				lettere[i][countl] = str[k]; countl++;
				parole2[i] = parole2[i]+to_string(ciSta(str[k],lettere[i]));	
			}
		}
	}
	int dimensioneParole = sizeof(parole2) / sizeof(parole2[0]);
	int max = -1;
	for (int i=0;i<T;i++) {
		if (count(parole2, parole2+dimensioneParole, parole2[i])>max) {
			max = count(parole2, parole2+dimensioneParole, parole2[i]);
		}
	}
	out << max;
}