#include <iostream>
#include <vector>
using Int = long long;
int main() {
	std::string S;
	std::cin >> S;
	int N = S.size();
	std::vector<char> sta;
	int cnt = 0;
	for (int i = 0; i < N; ++i) {
		if (S[i] == '<' || S[i] == '=') {
			sta.push_back(S[i]);
			cnt += S[i] == '<';
		}
		if (S[i] == '>') {
			if (cnt && sta.back() == '=') {
				while (sta.back() != '<') sta.pop_back();
				sta.pop_back();
				--cnt;
			} else {
				sta.push_back(S[i]);
				cnt = 0;
			}
		}
	}
	std::cout << sta.size() << std::endl;
}