Language: C++

v//inlclude before define 
#define _USE_MATH_DEFINES

//include
#include<iostream>
#include<string>
#include<algorithm>
#include<vector>
#include<cmath>
#include<type_traits>
#include<numeric>
#include<deque>
#include<iomanip>
#include<set>
#include<unordered_set>
#include<tuple>
#include<map>
#include<memory>

using namespace std;

//typedef
typedef vector<int> VI;
typedef vector<string> VS;
typedef vector<char> VC;
typedef vector<double> VD;
typedef pair<int, int> P1;
typedef long long int ll;

//number
#define INF 1e9
#define NUM 1000000007

//itr
#define all(x) begin(x),end(x)

//repeat
#define rep(i,n) for(int i=0;i<(int)(n);i++)
#define REP(i,a,b) for(int i=int(a);i<int(b);i++)
#define RREPS(i,x) for(int i=((int)(x));i>=0;i--)

//max,min
#define chmin(a,b) a=min((a),(b))
#define chmax(a,b) a=max((a),(b))

//function

/*ll gcd(ll a, ll b) {
	if (b == 0) return a;
	else return gcd(b, a%b);
}*/

/*ll lcm(ll a,ll b) {
	ll g = gcd(a, b);
	retur5n a * (b / g);
}*/

int dig(int a) {
	int sum = 0;
	while (a) {
		sum += a % 10;
		a /= 10;
	}
	return sum;
}

//grid template
int x[] = { -1, 0, 1, 0 };
int y[] = { 0,-1,0,1 };
int xx[] = { -1,-1,1,1 };
int yy[] = { 1,-1,1,-1 };

int main() {
	string s;
	cin >> s;
	int n;
	n = s.size();
	VC c = { 'A','T','G','C' };

	int ans = 0, cnt = 0;
	bool flag = false;
	rep(i, n) {
		flag = false;
		rep(j, 4) {
			if (c[j] == s[i]) flag = true;
		}

		if (flag) {
			cnt++;
		} else if(cnt!=0){
			ans = cnt;
			cnt = 0;
		}
		//cout << cnt << endl;
	}
	cout << ans << endl;
}

Compiler output:
a.cc:1:1: error: 'v' does not name a type
    1 | v//inlclude before define
      | ^
In file included from /usr/include/c++/14/iosfwd:42,
                 from /usr/include/c++/14/ios:40,
                 from /usr/include/c++/14/ostream:40,
                 from /usr/include/c++/14/iostream:41,
                 from a.cc:5:
/usr/include/c++/14/bits/postypes.h:68:11: error: 'ptrdiff_t' does not name a type
   68 |   typedef ptrdiff_t     streamsize; // Signed integral type
      |           ^~~~~~~~~
/usr/include/c++/14/bits/postypes.h:41:1: note: 'ptrdiff_t' is defined in header '<cstddef>'; this is probably fixable by adding '#include <cstddef>'
   40 | #include <cwchar> // For mbstate_t
  +++ |+#include <cstddef>
   41 | 
In file included from /usr/include/c++/14/bits/exception_ptr.h:38,
                 from /usr/include/c++/14/exception:166,
                 from /usr/include/c++/14/ios:41:
/usr/include/c++/14/new:131:26: error: declaration of 'operator new' as non-function
  131 | _GLIBCXX_NODISCARD void* operator new(std::size_t) _GLIBCXX_THROW (std::bad_alloc)
      |                          ^~~~~~~~
/usr/include/c++/14/new:131:44: error: 'size_t' is not a member of 'std'; did you mean 'size_t'?
  131 | _GLIBCXX_NODISCARD void* operator new(std::size_t) _GLIBCXX_THROW (std::bad_alloc)
      |                                            ^~~~~~
In file included from /usr/include/wchar.h:35,
                 from /usr/include/c++/14/cwchar:44,
                 from /usr/include/c++/14/bits/postypes.h:40:
/usr/lib/gcc/x86_64-linux-gnu/14/include/stddef.h:214:23: note: 'size_t' declared here
  214 | typedef __SIZE_TYPE__ size_t;
      |                       ^~~~~~
/usr/include/c++/14/new:132:41: error: attributes after parenthesized initializer ignored [-fpermissive]
  132 |   __attribute__((__externally_visible__));
      |                                         ^
/usr/include/c++/14/new:133:26: error: declaration of 'operator new []' as non-function
  133 | _GLIBCXX_NODISCARD void* operator new[](std::size_t) _GLIBCXX_THROW (std::bad_alloc)
      |                          ^~~~~~~~
/usr/include/c++/14/new:133:46: error: 'size_t' is not a member of 'std'; did you mean 'size_t'?
  133 | _GLIBCXX_NODISCARD void* operator new[](std::size_t) _GLIBCXX_THROW (std::bad_alloc)
      |                                              ^~~~~~
/usr/lib/gcc/x86_64-linux-gnu/14/include/stddef.h:214:23: note: 'size_t' declared here
  214 | typedef __SIZE_TYPE__ size_t;
      |                       ^~~~~~
/usr/include/c++/14/new:134:41: error: attributes after parenthesized initializer ignored [-fpermissive]
  134 |   __attribute__((__externally_visible__));
      |                                         ^
/usr/include/c++/14/new:140:29: error: 'std::size_t' has not been declared
  140 | void operator delete(void*, std::size_t) _GLIBCXX_USE_NOEXCEPT
      |                             ^~~
/usr/include/c++/14/new:142:31: error: 'std::size_t' has not been declared
  142 | void operator delete[](void*, std::size_t) _GLIBCXX_USE_NOEXCEPT
      |                               ^~~
/usr/include/c++/14/new:145:26: error: declaration of 'operator new' as non-function
  145 | _GLIBCXX_NODISCARD void* operator new(std::size_t, const std::nothrow_t&) _GLIBCXX_USE_NOEXCEPT
      |                          ^~~~~~~~
/usr/include/c++/14/new:145:44: error: 'size_t' is not a member of 'std'; did you mean 'size_t'?
  145 | _GLIBCXX_NODISCARD void* operator new(std::size_t, const std::nothrow_t&) _GLIBCXX_USE_NOEXCEPT
      |                                            ^~~~~~
/usr/lib/gcc/x86_64-linux-gnu/14/include/stddef.h:214:23: note: 'size_t' declared here
  214 | typedef __SIZE_TYPE__ size_t;
      |                       ^~~~~~
/usr/include/c++/14/new:145:52: error: expected primary-expression before 'const'
  145 | _GLIBCXX_NODISCARD void* operator new(std::size_t, const std::nothrow_t&) _GLIBCXX_USE_NOEXCEPT
      |                                                    ^~~~~
/usr/include/c++/14/new:147:26: error: declaration of 'operator new []' as non-function
  147 | _GLIBCXX_NODISCARD void* operator new[](std::size_t, const std::nothrow_t&) _GLIBCXX_USE_NOEXCEPT
      |                          ^~~~~~~~
/usr/include/c++/14/new:147:46: error: 'size_t' is not a member of 'std'; did you mean 'size_t'?
  147 | _GLIBCXX_NODISCARD void* operator new[](std::size_t, const std::nothrow_t&) _GLIBCXX_USE_NOEXCEPT
      |                                              ^~~~~~
/usr/lib/gcc/x86_64-linux-gnu/14/include/stddef.h:214:23: note: 'size_t' declared here
  214 | typedef __SIZE_TYPE__ size_t;
      |                       ^~~~~~
/usr/include/c++/14/new:147:54: error: expected primary-expression before 'const'
  147 | _GLIBCXX_NODISCARD void* operator new[](std::size_t, const std::nothrow_t&) _GLIBCXX_USE_NOEXCEPT
      |                                                      ^~~~~
/usr/include/c++/14/new:154:26: error: declaration of 'operator new' as non-function
  154 | _GLIBCXX_NODISCARD void* operator new(std::size_t, std::align_val_t)
      |                          ^~~~~~~~
/usr/include/c++/14/new:154:44: error: 'size_t' is not a member of 'std'; did you mean 'size_t'?
  154 | _GLIBCXX_NODISCARD void* operator new(std::size_t, std::align_val_t)
      |                                            ^~~~~~
/usr/lib/gcc/x86_64-linux-gnu/14/include/stddef.h:214:23: note: 'size_t' declared here
  214 | typedef __SIZE_TYPE__ size_t;
      |                       ^~~~~~
/usr/include/c++/14/new:154:68: error: expected primary-expression before ')' token
  154 | _GLIBCXX_NODISCARD void* operator new(std::size_t, std::align_val_t)
      |                                                                    ^
/usr/include/c++/14/new:155:73: error: attributes after parenthesized initializer ignored [-fpermissive]
  155 |   __attribute__((__externally_visible__, __alloc_size__ (1), __malloc__));
      |                                                                         ^
/usr/include/c++/14/new:156:26: error: declaration of 'operator new' as non-function
  156 | _GLIBCXX_NODISCARD void* operator new(std::size_t, std::align_val_t, const std::nothrow_t&)
      |                          ^~~~~~~~
/usr/include/c++/14/new:156:44: error: 'size_t' is not a member of 'std'; did you mean 'size_t'?
  156 | _GLIBCXX_NODISCARD void* operator new(std::size_t, std::align_val_t, const std::nothrow_t&)
      |                                            ^~~~~~
/usr/lib/gcc/x86_64-linux-gnu/14/include/stddef.h:214:23: note: 'size_t' declared here
  214 | typedef __SIZE_TYPE__ size_t;
      |                       ^~~~~~
/usr/include/c++/14/new:156:68: error: expected primary-expression before ',' token
  156 | _GLIBCXX_NODISCARD void* operator new(std::size_t, std::align_val_t, const std::nothrow_t&)
      |                                                                    ^
/usr/include/c++/14/new:156:70: error: expected primary-expression before 'const'
  156 | _GLIBCXX_NODISCARD void* operator new(std::size_t, std::align_val_t, const std::nothrow_t&)
      |                                                                      ^~~~~
/usr/include/c++/14/new:162:26: error: declaration of 'operator new []' as non-function
  162 | _GLIBCXX_NODISCARD void* operator new[](std::size_t, std::align_val_t)
      |                          ^~~~~~~~
/usr/include/c++/14/new:162:46: error: 'size_t' is not a member of 'std'; did you mean 'size_t'?
  162 | _GLIBCXX_NODISCARD void* operator new[](std::size_t, std::align_val_t)
      |                                              ^~~~~~
/usr/lib/gcc/x86_64-linux-gnu/14/include/stddef.h:214:23: note: 'size_t' declared here
  214 | typedef __SIZE_TYPE__ size_t;
      |                       ^~~~~~
/usr/include/c++/14/new:162:70: error: expected primary-expression before ')' token
  162 | _GLIBCXX_NODISCARD void* operator new[](std::size_t, std::align_val_t)
      |                                                                      ^
/usr/include/c++/14/new:163:73: error: attributes after parenthesized initializer ignored [-fpermissive]
  163 |   __attribute__((__externally_visible__, __alloc_size__ (1), __malloc__));
      |                                                                         ^
/usr/include/c++/14/new:164:26: error: declaration of 'operator new []' as non-function
  164 | _GLIBCXX_NODISCARD void* operator new[](std::size_t, std::align_val_t, const std::nothrow_t&)
      |                          ^~~~~~~~
/usr/include/c++/14/new:164:46: error: 'size_t' is not a member of 'std'; did you mean 'size_t'?
  164 | _GLIBCXX_NODISCARD void* operator new[](std::size_t, std::align_val_t, const std::nothrow_t&)
      |                                              ^~~~~~
/usr/lib/gcc/x86_64-linux-gnu/14/include/stddef.h:214:23: note: 'size_t' declared here
  214 | typedef __SIZE_TYPE__ size_t;
      |                       ^~~~~~
/usr/include/c++/14/new:164:70: error: expected primary-expression before ',' token
  164 | _GLIBCXX_NODISCARD void* operator new[](std::size_t, std::align_val_t, const std::nothrow_t&)
      |                                                                      ^
/usr/include/c++/14/new:164:72: error: expected primary-expression before 'const'
  164 | _GLIBCXX_NODISCARD void* operator new[](std::size_t, std::align_val_t, const std::nothrow_t&)
      |                                                                        ^~~~~
/usr/include/c++/14/new:171:29: error: 'std::size_t' has not been declared
  171 | void operator delete(void*, std::size_t, std::align_val_t)
      |                             ^~~
/usr/include/c++/14/new:173:31: error: 'std::size_t' has not been declared
  173 | void operator delete[](void*, std::size_t, std::align_val_t)
      |                               ^~~
/usr/include/c++/14/new:179:33: error: declaration of 'operator new' as non-function
  179 | _GLIBCXX_NODISCARD inline void* operator new(std::size_t, void* __p) _GLIBCXX_USE_NOEXCEPT
      |                                 ^~~~~~~~
/usr/include/c++/14/new:179:51: error: 'size_t' is not a member of 'std'; did you mean 'size_t'?
  179 | _GLIBCXX_NODI