#include <bits/stdc++.h>
using namespace std;

#define rep(i, n) for( int i = 0; i < n; i++ )
using ll = long long;

int main() {
	string s, t;
	cin >> s;
	int N = s.size();
	int f = 0;
	rep(i, N) {
		if(s[i] == '>') {
			if(f && t.back() == '=') {
				while(t.back() == '=') t.pop_back();
				t.pop_back();
				f--;
			}
			else {
				f = 0;
				t += s[i];
			}
		}
		else {
			if(s[i] == '<') f++;
			t += s[i];
		}
	}
	cout << t.size() << endl;
}