A. phone code

Time limit per test

2 seconds

Memory limit per test

256 megabytes

Input

Standard Input

Output

Standard output

Polycarpus hasNFriends in Tarasov city. polycarpus knows phone numbers of all his friends: they are stringsS_{1, bytes,S2, middle..., middle ,...,SN.
All these strings consist only of digits and have the same length.}

Once polycarpus needed to figure out Tarasov city phone code. he assumed that the phone code of the city is the longest common prefix of all phone numbers of his friends. in other words, it is the longest stringCWhich
Is a prefix (the beginning) of eachS_{IFor
AllI(1 digit ≤ DigitILimit ≤ limitN).
Help polycarpus determine the length of the city phone code.}

Input

The first line of the input contains an integerN(2 cores ≤ CoresNLimit ≤ limit 3 · 10^{4)
-The number of polycarpus's friends. The followingNLines contain stringsS_{1, bytes,S2, middle..., middle ,...,SN-
The phone numbers of polycarpus's friends. it is guaranteed that all strings consist only of digits and have the same length from 1 to 20,
Specified Sive. It is also guaranteed that all strings are different.}}

Output

Print the number of digits in the city phone code.

Sample test (s) Input

400209002190099900909

Output

2

Input

212

Output

0

Input

3770123456789999999997701234567890123456777012345678998765432

Output

12

Note

A prefix of stringTIs a string that is obtained by deleting zero or more
Digits from the end of stringT. For example, string "00209"
Has 6 prefixes: "" (an empty prefix), "0", "00 ",
"002", "0020", "00209 ".

In the first sample the city phone code is string "00 ".

In the second sample the city phone code is an empty string.

In the third sample the city phone code is string "770123456789 ".

Description: This question refers to finding the longest public prefix of a group of strings. The question describes the use of brute force algorithms. You only need to take the first POS character of the first string each time to form a new prefix string, and then loop. The strncmp function is used here to compare the first n characters of two strings.

#include <iostream>#include <cstdio>#include <cstdlib>#include <cmath>#include <cstring>#include <string>#include <algorithm>using namespace std;char a[30001][21];int main() {int n,i;int max;int k,pos;char c[21];scanf("%d",&n);for(i=0;i<n;i++){scanf("%s",&a[i]);}max=0;pos=1;while(1){k=0;for(i=0;i<pos;i++){c[k++]=a[0][i];}c[k]='\0';for(i=1;i<n;i++){if(strncmp(c,a[i],pos)!=0){break;}}if(i==n){max=pos;pos++;}else{break;}}printf("%d\n",max);return 0;}