#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;
struct dta{
  int n;
  int A,B;
};
bool cmp(const dta &a,dta &b){
  if(a.A==b.A){
    if(a.B==b.B){
      return a.n < b.n;
    }
    return a.B < b.B;
  }
  return a.A < b.A;

}
int nwa,nwb;
int main(){
  string s;cin>>s;
  vector<dta> A;
  A.push_back({-1,0,0});
  for(int i = 0; s.size() > i; i++){
    if(s[i] == 'A')nwa++;
    else nwb++;
    if(nwa*nwb){
      nwa--;
      nwb--;
    }
    A.push_back({i,nwa,nwb});
  }
  sort(A.begin(),A.end(),cmp);
  int nA = A[0].A;
  int nB = A[0].B;
  int nN = A[0].n;
  int ans = 0;
  for(int i = 1; A.size() > i; i++){
    if(nA == A[i].A && nB == A[i].B){
      cout << A[i].n << " " << nN << endl;
      ans = max(ans,A[i].n-nN);
    }else{
      nA = A[i].A;
      nB = A[i].B;
      nN = A[i].n;
    }
  }
  cout << ans << endl;
  
}