#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define REP(i, x, y) for (auto i = (x); i < (y); i++)
#define RREP(i, x, y) for (auto i = (y) - 1; (x) <= i; i--)
#define ALL(x) (x).begin(), (x).end()
#pragma GCC optimize("O3")
int main(){
  ios::sync_with_stdio(false);
  cin.tie(nullptr);
  string S;
  cin >> S;
  int N = ssize(S);
  stack<char> s;
  stack<char> t;
  REP(i, 0, N){
    if(S[i] == '<'){
      s.push('<');
      t.push('<');
    }
    if(S[i] == '='){
      s.push('=');
    }
    if(S[i] == '>'){
      if(!s.empty() && !t.empty() && s.top() == '=' && t.top() == '<'){
        while(s.top() == '='){
          s.pop();
        }
        s.pop();
        t.pop();
      }else{
        s.push('>');
        t.push('>');
      }
    }
  }
  cout << ssize(s) << "\n";
  return 0;
}
/*
  File : ~/yukicoder/midoriika_3rd/F.cpp
  Date : 2024/10/12
  Time : 14:46:06
*/