Language: C++

#include <iostream>
#include <cstdio>
#include <string>
#include <vector>
#include <algorithm>
#include <functional>
#include <iomanip>
#include <stdlib.h>
#include <string.h>
#include <cstring>
#include <cmath>
#include <map>
#include <queue>
#include <deque>
#include <stack>
#include <set>
#include <stdio.h>
#include <tuple>
#include <bitset>
#include <cfloat>
#include <fstream>
#include <limits.h>
#include <list>
#include <math.h>
#include <random>
#include <unordered_map>
#include <unordered_set>
#include <bitset>
#include <numeric>
#include <utility>
#include <sstream>

template<class T> inline bool chmin(T& a, T b) {
	if (a > b) {
		a = b;
		return true;
	}
	return false;
}
template<class T> inline bool chmax(T& a, T b) {
	if (a < b) {
		a = b;
		return true;
	}
	return false;
}

using namespace std;
#define int long long
#define ll long long
#define rep(i, n) for (ll i = 0; i < (n); i++)
#define FOR(i,a,b) for(ll i=(a);i<(b);i++)
#define FORR(i,a,b)for(ll i=(a);i<=(b);i++)
#define repr(i,n) for(ll i=n;i>=0;i--)
#define P pair<ll, ll>
#define sz(x) (ll)x.size()
#define ALL(x) (x).begin(),(x).end()
#define ALLR(x) (x).rbegin(),(x).rend()
#define VE vector<ll>
#define COUT(x) cout<<(x)<<endl
#define MA map<ll,ll>
#define SE set<ll>
#define PQ priority_queue<ll>
#define PQR priority_queue<ll,VE,greater<ll>>
#define COUT(x) cout<<(x)<<endl
#define YES(n) cout << ((n) ? "YES" : "NO"  ) << endl
#define Yes(n) cout << ((n) ? "Yes" : "No"  ) << endl
#define EPS (1e-10)
ll gcd(ll a, ll b) {
	if (a < b)swap(a, b);
	if (b == 0) return a;
	unsigned r;
	while ((r = a % b)) {
		a = b;
		b = r;
	}
	return b;
}
ll lcm(ll a, ll b) {
	ll g = gcd(a, b);
	return a / g * b;
}
bool prime(ll n) {
	for (ll i = 2; i <= sqrt(n); i++) {
		if (n%i == 0)return false;
	}
	return n != 1;
}
map<ll, ll> prime_factor(ll n) {
	map<ll, ll> ret;
	for (ll i = 2; i * i <= n; i++) {
		while (n % i == 0) {
			ret[i]++;
			n /= i;
		}
	}
	if (n != 1) ret[n] = 1;
	return ret;
}

const long long MOD = 1000000007;
//const long long MOD = 998244353;
const long long INF = 1LL << 60;



const long double PI = 3.14159265359;
const int MAX_N = 100010;


signed main() {
	ios_base::sync_with_stdio(0);
	cin.tie(0);
	int n; cin >> n;
	vector<string> s(n); rep(i, n)cin >> s[i];
	int ans = 0;
	rep(i, n) {
		rep(j, s[i].size() - 1) {
			if (s[i][j] == 'A'&&s[i][j + 1] == 'B')ans++;
		}
	}
	int ab = 0, a = 0, b = 0;
	rep(i, n) {
		if (s[i][0] == 'B'&&s[i][s[i].size - 1] == 'A')ab++;
		else if (s[i][0] == 'B')b++;
		else if (s[i][s[i].size() - 1] == 'A')a++;
	}
	if (ab == 0)cout << ans + min(a, b) << endl;
	else {
		if (a + b > 0)cout << ans + min(a, b) << endl;
		else cout << ans + ab - 1 << endl;
	}
	return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:124:47: error: invalid use of member function 'std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::size_type std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::size() const [with _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>; size_type = long unsigned int]' (did you forget the '()' ?)
  124 |                 if (s[i][0] == 'B'&&s[i][s[i].size - 1] == 'A')ab++;
      |                                                   ()