#include <bits/stdc++.h>

using namespace std;
using ll = long long;

int main(){
    cin.tie(nullptr);
    ios_base::sync_with_stdio(false);

    string S, T="", U="";
    cin >> S;
    for (auto x : S){
        if (x == '>'){
            if (T.size() == 0 || U.size() == 0 || T.back() != '=' || U.back() != '<'){
                T += x;
                U += x;
                continue;
            }
            while(T.back() == '='){
                T.pop_back();
            }
            T.pop_back();
            U.pop_back();
        }
        else if (x == '<'){
            U += x;
            T += x;
        }
        else T += x;
    }
    cout << T.size() << endl;

    return 0;
}