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

int main() {
    string S;
    cin >> S;
    vector<pair<char, int>> T;
    T.push_back({S[0], 0});
    for (int i = 1; i < (int)S.size(); i++) {
        if (S[i - 1] == '=' && S[i] == '=') {
            //
        } else {
            T.push_back({S[i], i});
        }
    }
    stack<pair<char, int>> st;
    vector<int> imos((int)S.size() + 1, 0);
    cout << endl;
    for (int i = 0; i < (int)T.size(); i++) {
        st.push(T[i]);
        while ((int)st.size() >= 3) {
            auto [a, x] = st.top();
            st.pop();
            auto [b, y] = st.top();
            st.pop();
            auto [c, z] = st.top();
            st.pop();
            string abc = "";
            abc += c;
            abc += b;
            abc += a;
            // cout << "### " << abc << endl;
            if (abc == "<=>") {
                imos[z]++;
                imos[x + 1]--;
            } else {
                st.push({c, z});
                st.push({b, y});
                st.push({a, x});
                break;
            }
        }
    }
    for (int i = 0; i < (int)S.size(); i++) {
        imos[i + 1] += imos[i];
    }
    int ans = 0;
    for (int i = 0; i < (int)S.size(); i++) {
        if (imos[i] == 0) {
            ans++;
        }
    }
    cout << ans << endl;
    return 0;
}