#include <bits/stdc++.h>

using namespace std;

#define int long long

string s;

pair<int, int> f(int idx); // 宣告

pair<int, int> expre(int idx){ // Expression 計算

    stack<int> stk;

    string op = "#"; // operators

    while (idx < (int)s.size() && !(s[idx] == ',' || s[idx] == ')')){

        int temp = 0;

        if (s[idx] == '+' || s[idx] == '*'){

            op = s[idx++];

            continue;

        }

        else if (s[idx] == 'f'){

            pair<int, int> buffer = f(idx + 2); //+2 後會是數字

            idx = buffer.first;

            temp = buffer.second;

        }

        else{

            while (s[idx] >= 48 && s[idx] <= 57){

                temp *= 10;

                temp += (s[idx++] - 48);

            }

        }

        if (op == "+"){ // op[0]=='+'

            temp += stk.top();

            stk.pop();

            stk.push(temp);

        }

        else if (op[0] == '*' && stk.size() >= 2){

            int ta = stk.top();

            stk.pop();

            ta *= stk.top();

            stk.pop();

            stk.push(ta);

            stk.push(temp);

        }

        else stk.push(temp);

    }

    if (stk.size() >= 2){

        int ta = stk.top();

        stk.pop();

        ta *= stk.top();

        stk.pop();

        stk.push(ta);

    }

    return {idx, stk.top()};

}

pair<int, int> f(int idx){ // 計算 f 函式

    pair<int, int> temp = expre(idx);

    int mx, mn = temp.second;

    mx = mn;

    idx = temp.first;

    while (s[idx++] != ')'){ // 注意這裡的 idx++

        temp = expre(idx);

        idx = temp.first;

        mx = max(mx, temp.second);

        mn = min(mn, temp.second);

    }

    return {idx, (mx - mn)};

}

signed main(){

    cin >> s;

    cout << expre(0).second;

}