#include <bits/stdc++.h>

[[nodiscard]] static inline constexpr uint_fast32_t solve(const std::string& S) noexcept
{
	uint_fast32_t ans = 0;
	for (uint_fast32_t i = 0; i != S.size(); ++i)
		if (std::isdigit(S[i]))
			ans += S[i] - '0';

	return ans;
}

int main()
{
	std::cin.tie(nullptr);
	std::ios::sync_with_stdio(false);
	
	std::string S;
	S.reserve(10'000);
	std::cin >> S;

	std::cout << solve(S) << '\n';
	return 0;
}