#include <bits/stdc++.h>
using namespace std;
int main(){
	string S;
	cin >> S;
	string T;
	int cnt = 0;
	for (char c : S){
		if (c == '>' and cnt > 0){
			if (T.back() != '='){
				T += c;
				cnt = 0;
				continue;
			}
			while (T.back() == '='){
				T.pop_back();
			}
			T.pop_back();
			cnt--;
		} else {
			if (c == '<'){
				cnt++;
			}
			T += c;
		}
	}
	cout << T.size() << endl;
}