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++14 (GCC 5.4.1) (judge verdict: Accepted)

#include <bits/stdc++.h>
using namespace std;

using ll = long long;
#define ld long double
#define ull unsigned long long int

#define rep(i, n) for (int i = 0; i < (int)(n); i++)  // (i, 10) i=0～i=9まで
#define repr(i, n) for (int i = n; i >= 0; i--)   // (i, 10) i=10～i=0まで
#define FOR(i, m, n) for (int i = m; i < n; i++)  // (i, 3, 10) i=3～i=9まで
#define SORT(v, n) sort(v, v + n);
#define VSORT(v) sort(v.begin(), v.end());
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
#define sz(x) ((int)(x).size())
#define pb push_back
#define ret return

typedef pair<int, int>    pii;
typedef vector<int>       vi;
typedef vector<vi>        vii;
typedef vector<long long> vl;

// 総数を1000000007で割った余り
const long long mod = 1e9 + 7;
#define EPS (1e-7)
#define INF (1e9)
#define PI (acos(-1))

int main() {
    // cin.tie(0);
    // ios::sync_with_stdio(false);
    // cout << fixed << setprecision(5);

    // 入力
    string s;
    cin >> s;

    // 処理
    int cnt = 0;
    int ans = 0;
    rep(i, s.size()) {
        if (s[i] == 'A' || s[i] == 'C' || s[i] == 'G' || s[i] == 'T') {
            cnt++;
            ans = max(cnt, ans);
        } else {
            cnt = 0;
        }
    }

    // 出力
    cout << ans << endl;

    return 0;
}