#include<iostream>
#include<string>
using namespace std;

int main() {

	int result = 0;
	string input = "";
	cin >> input;

	int tempN = 0;
	for (int i = 0; i < input.size(); i++) {
		if (int(input.at(i)) < 83) {
			tempN = (int(input.at(i)) - 56) / 3;
		}
		else if (int(input.at(i)) != 90) {
			tempN = (int(input.at(i)) - 57) / 3;
		}
		else {
			tempN = (int(input.at(i)) - 58) / 3;
		}
		result += tempN;
	}

	cout << result << endl;

	return 0;
}