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)

/* ex 5_4
   nnasy */

#include <stdio.h>
//最大入力量より大きいサイズをとる
#define SIZE 30

int main(void){
    //str: 与えられた文字列を格納する配列
    //ptr: strの各要素へのポインタ
    char str[SIZE], *ptr;
    //count: str内のAGCT文字列のそれぞれの長さを調べるための整数
    //max: countの最大値を入れておく整数
    int count=0, max=0;

    //与えられた文字列を入力
    scanf("%s", str);

    //ptrにstrのアドレスを代入
    ptr = str;

    //ptrの位置が'\0'になるまでwhile文を動かす
    while(*ptr){
        //ptrの位置がAGCTのいずれかならcountを1増やし、アドレスをずらす
        if (*ptr=='A' || *ptr=='G' || *ptr=='C' || *ptr=='T'){
            count++;
            ptr++;
        //ptrの位置がAGCTのいずれでもないときmax値を調べる
        }else{
            if (count>max){
                max=count;
            }
            //countしなおすので0に戻し、アドレスをずらす
            count=0;
            ptr++;
        }
    }

    //文字列の末尾がAGCTのいずれかのとき最大長が変わる可能性がある
    if (count>max){
        max=count;
    }

    //入力した文字列の部分文字列のうち最も長いACGT文字列の長さを出力
    printf("%d\n", max);

    return 0;
}