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
   TakayukiY*/

#include<stdio.h>

int main(void){
    //10文字以下の入力なので11文字分確保、ポインターの定義
    char seqence[11],*ptr;
    //インデックスと最大の長さの定義
    int i=0,max=0;
    //文字列を格納
    scanf("%s",seqence);
    //ポインターを格納
    ptr=seqence;

    while(*ptr){
        //ACGTの文字が現れたとき、現在の連続数iに1を加える
        if(*ptr=='A'||*ptr=='C'||*ptr=='G'||*ptr=='T'){
            i++;
        }
        //ACGT以外の文字が現れたとき、連続数iが今までの最大を超えれば更新
        //連続数iを初期化
        else{
            if(max<i) max=i;
            i=0;
        }
        ptr++;
    }
    //最後の文字までACGTだった場合の更新
    if(max<i) max=i;

    printf("%d",max);

    return 0;
}