#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
#define all(x) (x).begin(), (x).end()
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define rrep(i, n) for(int i = (int)(n - 1); i >= 0; i--)
template <typename T> bool chmax(T &a,const T &b){if(a<b){a=b;return true;}return false;}
template <typename T> bool chmin(T &a,const T &b){if(a>b){a=b;return true;}return false;}
using ll = long long;
#define int ll
using vi = vector<int>;
using vvi = vector<vector<int>>;
using vb = vector<bool>;
using vvb = vector<vector<bool>>;
using vs = vector<string>;
using pii = pair<int, int>;
// using mint = modint!!!number!!!;

signed main(){
  string s; cin >> s;
  int n = size(s);
  deque<char> q;
  vb ok(n, false);
  rep(i, n){
  	if(s.at(i) == '<'){
  		q.push_back(s.at(i));
  		ok.at(i) = true;
  	}
  	else if(s.at(i) == '>'){
  		if(!q.empty() && ok.at(i - 1) && q.back() == '='){
  			int cnt = 1;
  			while(q.back() == '='){
  				q.pop_back();
  				cnt++;
  			}
  			q.pop_back();
  			ok.at(i) = ok.at(i - cnt);
  		}
  		else{
  			q.push_back(s.at(i));
  			ok.at(i) = false;
  		}
  	}
  	else{
  		q.push_back(s.at(i));
  		ok.at(i) = (i == 0 ? false : ok.at(i - 1));
  	}
  }
  cout << q.size() << endl;
  /*
  while(!q.empty()){
  	cerr << q.front();
  	q.pop_front();
  }
  */
}