#include<bits/stdc++.h> 
#define ri register
using namespace std;
template <class O>
inline void read(O &x) {ri char c = getchar();x=0;for (; !isdigit(c); c = getchar());for (; isdigit(c); c = getchar()) x = x * 10 + (c ^ 48);return;}
int n,t,top=1;
string s,a;
signed main(){
	read(t);
	for(ri int x=1;x<=t;x++){
		cin>>s;
		n=s.size();
		for(ri int i=0;i<n;i++){
			a[++top]=s[i];
			if(a[top]=='B'&&a[top-1]=='A'){
				top-=2;
			}if(a[top]=='B'&&a[top-1]=='B'){
				top-=2;
			}
		}printf("%d\n",top-1);
		top=1;
		cout<<x<<' '<<t;
	}
	return 0;
}

这个程序为什么$s$一变长就RE了？