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: Wrong Answer)

/* mytemplate.cpp {{{ */

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

/* rep */
#define GET_MACRO(_1, _2, _3, _4, NAME, ...) NAME
#define rep(...) GET_MACRO(__VA_ARGS__, rep4, rep3, rep2, rep1)(__VA_ARGS__)
#define rep1(n) rep2(_, n)
#define rep2(i, n) rep3(i, 0, n)
#define rep3(i, a, n) rep4(i, a, n, 1)
#define rep4(i, a, n, s) for (ll i = (a); i < (ll)(n); i += (s))
#define per(...) GET_MACRO(__VA_ARGS__, per4, per3, per2, per1)(__VA_ARGS__)
#define per1(a) per2(_, a)
#define per2(i, a) per3(i, a, 0)
#define per3(i, a, n) per4(i, a, n, 1)
#define per4(i, a, n, s) for (ll i = (a); i >= (ll)(n); i -= (s))
#define each(x, c) for(auto&& x : c)

/* short */
#define pb push_back
#define mp make_pair
#define fi first
#define se second
#define all(c) (c).begin(), (c).end()
#define len(c) ((ll)(c).size())
#define temp_T template<typename T>
#define temp_TU template<typename T, typename U>

/* debug */
#define debug(x) {cerr << #x << " = " << (x) << "\n";}

/* alias */
temp_T using vec = vector<T>;
temp_T using heap = priority_queue<T>;
temp_T using minheap = priority_queue<T, vec<T>, greater<T>>;
using ll = long long;
using str = string;
using vi = vec<ll>;
using vvi = vec<vi>;
using vs = vec<str>;
using vb = vec<bool>;
using pii = pair<ll, ll>;

/* const */
const int INF = 1e9;
const int MOD = 1e9 + 7;
const double EPS = 1e-9;
const double PI = acos(-1);
const int dx[] = {0, 1, 0, -1};
const int dy[] = {1, 0, -1, 0};

/* function */
inline ll gcd(ll a, ll b) {return b ? gcd(b, a % b) : a;}
inline ll lcm(ll a, ll b) {return a * b / gcd(a, b);}
inline ll minMultiple(ll a, ll n) {return n * (a / n + (a % n == 0 ? 0 : 1));}
bool isPrime(ll n) {if (n < 2) return false; rep(i, 2, (sqrt(n) + 1)) {if (n % i == 0) return false;} return true;}
void eratosthenes(vb& primes) {rep(i, len(primes)) primes[i] = true; primes[0] = primes[1] = false; rep(i, len(primes) / 2 + 1) {if (primes[i]) {rep(j, i + i, len(primes), i) primes[j] = false;}}}
vi listDivisors(ll n) { vi divs; rep(i, 1, sqrt(n) + 1) { if (n % i == 0) {divs.pb(i); divs.pb(n / i);}} sort(all(divs)); return divs; }
map<ll, ll> primeFactorize(ll n) {map<ll, ll> prime_factors; ll m = n; rep(i, 2, sqrt(n) + 1) {if (m < 1) break; while (m % i == 0) {++prime_factors[i]; m /= i;}} if (m != 1) ++prime_factors[m]; return prime_factors;}
inline ll mod_add(ll a, ll b) {return (a + b) % MOD;}
inline ll mod_sub(ll a, ll b) {return (a + MOD - b) % MOD;}
inline ll mod_mul(ll a, ll b) {return ((a % MOD) * (b % MOD)) % MOD;}
ll mod_pow(ll x, ll y) {if (y == 0) return 1; else if (y == 1) return x % MOD; else if (y % 2 == 0) {ll val = mod_pow(x, (ll)(y / 2)); return mod_mul(val, val);} else {ll val = mod_pow(x, (ll)(y / 2)); return mod_mul(mod_mul(val, val), x);}}
ll mod_inv(ll x) {return mod_pow(x, MOD - 2);}
ll mod_div(ll a, ll b) {return mod_mul(a, mod_inv(b));}
ll fact(ll n) {return n == 0 ? 1 : mod_mul(n, fact(n - 1));}
ll comb(ll n, ll r) {return fact(n) / fact(n - r) / fact(r);}
temp_T inline bool chmax(T& a, const T b) {if (a < b) a = b; return a < b;}
temp_T inline bool chmin(T& a, const T b) {if (a > b) a = b; return a > b;}
template<typename T = ll> inline T in() {T x; cin >> x; return x;}
temp_T inline void print(const T& x) {cout << x << "\n";}
temp_T inline void print(const vector<T>& v) {rep(i, len(v)) cout << v[i] << (i != len(v) - 1 ? " " : "\n");}
temp_TU inline void print(const pair<T, U>& p) {cout << p.fi << " " << p.se << "\n";}
temp_TU inline void print(const map<T, U>& d) {each(x, d) print(x);}

/* init */
struct Init {Init(){cin.tie(nullptr); ios::sync_with_stdio(false); cout << fixed << setprecision(10);}} init;

/* }}} */


//-----------------------------------------------------------------------------


int main() {
    str S = in<str>();
    ll Slen = len(S), l = 0, ma = 0;
    bool flag = false;
    rep(i, Slen) {
        if (S[i]=='A'||S[i]=='C'||S[i]=='G'||S[i]=='T') {
            if (!flag) flag = !flag;
            if (flag) ++l;
        }
        else {
            if (flag) {
                flag = !flag;
                chmax(ma, l);
                l = 0;
            }
            if (!flag) continue;
        }
    }
    print(ma);
}