Problem:
Score : 200 points

Problem Statement

You are given a string S consisting of uppercase English letters. Find the length of the longest ACGT string that is a substring (see Notes) of S.

Here, a ACGT string is a string that contains no characters other than A, C, G and T.

Notes

A substring of a string T is a string obtained by removing zero or more characters from the beginning and the end of T.

For example, the substrings of ATCODER include TCO, AT, CODER, ATCODER and (the empty string), but not AC.

Constraints

S is a string of length between 1 and 10 (inclusive).

Each character in S is an uppercase English letter.

Input

Input is given from Standard Input in the following format:

S

Output

Print the length of the longest ACGT string that is a substring of S.

Sample Input 1

ATCODER

Sample Output 1

3

Among the ACGT strings that are substrings of ATCODER, the longest one is ATC.

Sample Input 2

HATAGAYA

Sample Output 2

5

Among the ACGT strings that are substrings of HATAGAYA, the longest one is ATAGA.

Sample Input 3

SHINJUKU

Sample Output 3

0

Among the ACGT strings that are substrings of SHINJUKU, the longest one is (the empty string).

Solution in C (GCC 9.2.1) (judge verdict: Accepted)

/* h-ex5_4
   Ohshima */

#include <stdio.h>

int main(void){
  //10文字以下なので最大の要素数は\0を含めて11
  //ptr: strの各要素へのポインタ
  char str[11], *ptr;
  //len: ACGT部分文字列が続く場合にその長さを保持しておくための変数
  //max_len: 上のような長さlenのうち最大値を保持しておくための変数, 最終的にはこれを出力
  int len = 0, max_len = 0;
  scanf("%s", str);
  ptr = str;
  //ACGT部分文字列があるかどうかを調べる, 条件式は*ptr != '\0'と同義
  while(*ptr){
    //調べている文字がACGTに該当するなら長さlenを1だけ増やす
    if(*ptr == 'A' || *ptr == 'C' || *ptr == 'G' || *ptr == 'T'){
      len++;
    }else{
      //途中でACGT以外の文字が現れた場合は、その時点でのACGT部分文字列の長さが最大かどうかを調べ、その後lenをリセット
      if(len > max_len){
        max_len = len;
      }
      len = 0;
    }
    ptr++;
  }
  //ACGT部分文字列が続いている途中でループが終了した場合も考慮
  if(len > max_len){
    max_len = len;
  }
  printf("%d\n", max_len);
  return 0;
}