#include <bits/stdc++.h>
#define all(x) (x).begin(),(x).end()
using namespace std;
const int MSIZE = 10101;

bool Kek(char ch) {
    return (ch >= 'a' && ch <= 'z') || (ch >= 'A' && ch <= 'Z');
}

pair<bool, string> TypicalBadString(string& s, int type = 1) {
    if (s == "") return {0, ""};
    for (char ch : s) if (ch == '\n') return {0, ""};
    string name = "";
    for (char ch : s) {
        if (!Kek(ch)) {
            if (!type) return {0, ""};
            if (ch != ' ') {
                return {0, ""};
            } else {
                return {1, name};
            }
        } else {
            name += ch;
        }
    }
    return {1, name};
}

const int NSIZE = 505;

int dp[NSIZE][NSIZE];

int main() {
#ifdef LOCAL
    freopen("input.txt", "r", stdin);
    freopen("output.txt", "w", stdout);
#endif
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    string s;
    char ch;
    while (ch = getchar()) {
        if (ch == EOF) break;
        s.push_back(ch);
    }
    vector<string> tag;
    int left = 0;
    int right = 0;
    bool bad = false;
    int ans = 0;
    int n = s.size();
    for (int i = 0; i < n; i++) {
        if (s[i] == '<') left = i;
        if (s[i] == '>') {
            tag.push_back(s.substr(left + 1, i - left - 1));
        }
    }
    vector<pair<string, int> > begins;
    vector<pair<string, int> > ends;
    int itr = 0;
    for (auto& s : tag) {
        if (s.size() == 0) {
            ans++;
        } else if (s[0] != '/') {
            auto [type, name] = TypicalBadString(s);
            if (name == "") ans++;
            else begins.push_back({name, itr});
        } else {
            s = s.substr(1, s.size() - 1);
            auto [type, name] = TypicalBadString(s, 0);
            if (name == "") ans++;
            else ends.push_back({name, itr});
        }
        itr++;
    }
    set<string> st;
    for (auto [str, ind] : begins) st.insert(str);
    for (auto [str, ind] : ends) st.insert(str);
    map<string, int> mp;
    itr = 1;
    for (string str : st) mp[str] = itr++;
    vector<pair<int,int> > full;
    for (auto [str, ind] : begins) full.push_back({ind, mp[str]});
    for (auto [str, ind] : ends) full.push_back({ind, -mp[str]});
    memset(dp, 0, sizeof dp);
    sort(all(full));
    vector<int> a;
    for (auto [ind, val] : full) a.push_back(val);
    n = a.size();
    for (int len = 1; len <= n; len++) {
        for (int l = 0; l + len <= n; l++) {
            int r = l + len - 1;
            if (l == r) {
                continue;
            } else {
                for (int i = l; i <= r; i++) {
                    dp[l][r] = max(dp[l][r], dp[l][i] + dp[i + 1][r]);
                }
                if (a[l] == -a[r] && a[l] == abs(a[l])) {
                    dp[l][r] = max(dp[l][r], dp[l + 1][r - 1] + 1);
                }
            }
        }
    }
    int used = dp[0][n - 1];
    cout << ans + a.size() - used * 2 << endl;
}