//#define _GLIBCXX_DEBUG
#include <bits/stdc++.h>
#pragma GCC optimize("O3")
#define count masloriy1489
#define y1 jhgfds
#define prev maAslo
#define ll long long
#define ld long double
#define pb push_back
#define eb emplace_back
#define all(v) v.begin(), v.end()
#define rep(i, n) for(int i = 0; i < n; i++)

using namespace std;
//freopen("input.txt", "r", stdin);
//freopen("output.txt", "w", stdout);
//cout << clock()*1000/CLOCKS_PER_SEC << '\n';

stack<int> num;
stack<char> op;

inline void make(){
    int a = num.top();
    num.pop();
    int b = num.top();
    num.pop();
    char c = op.top();
    op.pop();
    if(c == '+')
        num.push(a + b);
    else
        num.push(b - a);
}

int32_t main(){
    ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
    //freopen("evalpm.in", "r", stdin);
    //freopen("evalpm.out", "w", stdout);
    int curr = 0;
    string s;
    cin >> s;
    bool f = false;
    op.push('(');
    s += ')';
    for(char c : s){
        if(c >= '0' && c <= '9'){
            curr = curr*10 + (c - '0');
            f = true;
        }else{
            if(f){
                num.push(curr);
                f = false;
                curr = 0;
            }
            if(c == ')'){
                while(!op.empty() && op.top() != '('){
                    make();
                }
                if(!op.empty())
                    op.pop();
                if(!op.empty()){
                    if(op.top() == '-'){
                        op.pop();
                        op.push('+');
                        int g = num.top();
                        num.pop();
                        num.push(-g);
                    }
                }
            }else{
                op.push(c);
            }
        }
    }
    cout << num.top();
}