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 PyPy3 (2.4.0) (judge verdict: Runtime Error)

import sys
sys.setrecursionlimit(10000000)
import numpy as np
from heapq import heapify, heappop, heappush
import copy
from collections import deque
# queueとして使う場合 push, popleftを使う
from bisect import bisect_left, bisect_right
# bisect_left: 配列の順序関係が崩れない条件で挿入することができる一番左の点
# bisect_right: 配列の順序関係が崩れない条件で挿入することができる一番右の点
# A = [1, 1, 1, 2, 2, 2, 4]
# print(bisect_left(A, 2))  # 3
# print(bisect_right(A, 2))  # 6
# print(bisect_left(A, 3))  # 6
# print(bisect_right(A, 3))  # 6


def main():
    S = input()
    max_num = 0
    num = 0
    for i in S:
        if i in ['A', 'T', 'G', 'C']:
            num += 1
            max_num = max(num, max_num)
        else:
            num = 0
    print(max_num)



if __name__ == '__main__':
    main()