#pragma GCC optimize ("O3") #pragma GCC target ("avx") #include "bits/stdc++.h" using namespace std; using ll = long long int; #define debug(v) {printf("L%d %s > ",__LINE__,#v);cout<<(v)< ",__LINE__,#v);for(auto e:(v)){cout< ",__LINE__,#m);for(int x=0;x<(w);x++){cout<<(m)[x]<<" ";}cout<\n",__LINE__,#m);for(int y=0;y<(h);y++){for(int x=0;x<(w);x++){cout<<(m)[y][x]<<" ";}cout<::type cnt=0;(cnt)<(l);++(cnt)) #define rrepeat(cnt,l) for(auto cnt=(l)-1;0<=(cnt);--(cnt)) #define iterate(cnt,b,e) for(auto cnt=(b);(cnt)!=(e);++(cnt)) #define diterate(cnt,b,e) for(auto cnt=(b);(cnt)!=(e);--(cnt)) const ll MD = 1000000007ll; const long double PI = 3.1415926535897932384626433832795L; template inline void assert_equal(T1 expected, T2 actual) { if (!(expected == actual)) { cerr << "assertion fault: expected=" << expected << " actual=" << actual << endl; abort(); } } template inline void assert_less(T1 actual, T2 threshold) { if (!(actual < threshold)) { cerr << "assertion fault: " << actual << " < (const)" << threshold << endl; abort(); } } template inline void assert_eqless(T1 actual, T2 threshold) { if (!(actual <= threshold)) { cerr << "assertion fault: " << actual << " <= (const)" << threshold << endl; abort(); } } template inline ostream& operator <<(ostream &o, const pair p) { o << '(' << p.first << ':' << p.second << ')'; return o; } template inline ostream& _ostream_vecprint(ostream &o, const Vec& p) { o << '['; for (auto& e : p) o << e << ','; o << ']'; return o; } template inline ostream& operator<<(ostream& o, const vector& v) { return _ostream_vecprint(o, v); } template inline ostream& operator<<(ostream& o, const array& v) { return _ostream_vecprint(o, v); } template inline T& maxset(T& to, const T& val) { return to = max(to, val); } template inline T& minset(T& to, const T& val) { return to = min(to, val); } void bye(string s, int code = 0) { cout << s << endl; exit(code); } mt19937_64 randdev(8901016); template inline T rand(T l, T h) { return uniform_int_distribution(l, h)(randdev); } template<> inline double rand(double l, double h) { return uniform_real_distribution(l, h)(randdev); } template<> inline float rand(float l, float h) { return uniform_real_distribution(l, h)(randdev); } #if defined(_WIN32) || defined(_WIN64) #define getchar_unlocked _getchar_nolock #define putchar_unlocked _putchar_nolock #elif defined(__GNUC__) #else #define getchar_unlocked getchar #define putchar_unlocked putchar #endif namespace { #define isvisiblechar(c) (0x21<=(c)&&(c)<=0x7E) class MaiScanner { public: template void input_integer(T& var) { var = 0; T sign = 1; int cc = getchar_unlocked(); for (; cc<'0' || '9'>(int& var) { input_integer(var); return *this; } inline MaiScanner& operator>>(long long& var) { input_integer(var); return *this; } inline MaiScanner& operator>>(string& var) { int cc = getchar_unlocked(); for (; !isvisiblechar(cc); cc = getchar_unlocked()); for (; isvisiblechar(cc); cc = getchar_unlocked()) var.push_back(cc); return *this; } template void in(IT begin, IT end) { for (auto it = begin; it != end; ++it) *this >> *it; } }; class MaiPrinter { public: template void output_integer(T var) { if (var == 0) { putchar_unlocked('0'); return; } if (var < 0) putchar_unlocked('-'), var = -var; char stack[32]; int stack_p = 0; while (var) stack[stack_p++] = '0' + (var % 10), var /= 10; while (stack_p) putchar_unlocked(stack[--stack_p]); } inline MaiPrinter& operator<<(char c) { putchar_unlocked(c); return *this; } inline MaiPrinter& operator<<(int var) { output_integer(var); return *this; } inline MaiPrinter& operator<<(long long var) { output_integer(var); return *this; } inline MaiPrinter& operator<<(char* str_p) { while (*str_p) putchar_unlocked(*(str_p++)); return *this; } inline MaiPrinter& operator<<(const string& str) { const char* p = str.c_str(); const char* l = p + str.size(); while (p < l) putchar_unlocked(*p++); return *this; } template void join(IT begin, IT end, char sep = '\n') { for (auto it = begin; it != end; ++it) *this << *it << sep; } }; } MaiScanner scanner; MaiPrinter printer; int N, M, K; string str; int sum[200010]; int low[400010], high[400010]; int main() { scanner >> str; N = str.size(); const int inf = int(1e9); fill(low, low + 400000, inf); low[N+1] = 0; repeat(i, N) { sum[i + 1] = sum[i] + (str[i] == 'A' ? 1 : -1); minset(low[N+1+sum[i + 1]], i+1); maxset(high[N+1+sum[i + 1]], i+1); } int ans = 0; repeat(i, N*2+5) { int k = high[i] - low[i]; maxset(ans, k); } cout << ans << endl; return 0; }