Untitled

#include <iostream>
#include <string>

using namespace std;

int main()
{
	//1
	string s;
	cin >> s;
	
	int count_a = 0;

	for (int i = 0; i < s.length(); i++) {
		if (s[i] == 'a') {
			count_a += 1;
		}
	}
	cout << count_a;
}