#include <iostream>
#include <sstream>
#include <cstdio>
#include <cstdlib>
#include <cmath>
#include <ctime>
#include <cstring>
#include <string>
#include <vector>
#include <stack>
#include <queue>
#include <deque>
#include <map>
#include <set>
#include <bitset>
#include <numeric>
#include <utility>
#include <iomanip>
#include <algorithm>
#include <functional>
using namespace std;

typedef long long ll;
typedef vector<int> vint;
typedef vector<ll> vll;
typedef pair<int,int> pint;

#define DE 1
#define FI first
#define SE second
#define PB push_back
#define MP make_pair
#define ALL(s) (s).begin(),(s).end()
#define REP(i,n) for (int i = 0; i < (int)(n); ++i)
#define EACH(i,s) for (typeof((s).begin()) i = (s).begin(); i != (s).end(); ++i)
#define COUT(x) cout<<#x<<" = "<<(x)<<" (L"<<__LINE__<<")"<<endl

template<class T1, class T2> ostream& operator<<(ostream &s, pair<T1,T2> P){return s<<'<'<<P.first<<", "<<P.second<<'>';}
template<class T> ostream& operator<<(ostream &s, vector<T> P) {s<<"{ ";for(int i=0;i<P.size();++i){if(i>0)s<<", ";s<<P[i];}return s<<" }"<<endl;}
template<class T1, class T2> ostream& operator<<(ostream &s, map<T1,T2> P) {s<<"{ ";for(typeof(P.begin()) it=P.begin();it!=P.end();++it){if(it!=P.begin())s<<", ";s<<'<'<<it->first<<"->"<<it->second<<'>';}return s<<" }"<<endl;}



const int INF = 10000;
template<class T> struct comp {
    T x, y;
    comp(T x = 0, T y = 0) : x(x), y(y) {}
    friend ostream& operator << (ostream &s, const comp<T> &p) {return s << '(' << p.x << ", " << p.y << ')';}
};

template<class T> comp<T> operator + (comp<T> p, comp<T> q) {return comp<T>(p.x + q.x, p.y + q.y);}
template<class T> comp<T> operator - (comp<T> p, comp<T> q) {return comp<T>(p.x - q.x, p.y - q.y);}
template<class T> comp<T> operator * (comp<T> p, T a) {return comp<T>(p.x * a, p.y * a);}
template<class T> comp<T> operator * (T a, comp<T> p) {return comp<T>(a * p.x, a * p.y);}
template<class T> comp<T> operator * (comp<T> p, comp<T> q) {return comp<T>(p.x * q.x - p.y * q.y, p.x * q.y + p.y * q.x);}
template<class T> comp<T> operator / (comp<T> p, T a) {return comp<T>(p.x / a, p.y / a);}



bool isvalid(comp<ll> a) {
    if (a.x > INF || a.x < -INF || a.y > INF || a.y < -INF) return false;
    else return true;
}



// 構文解析
typedef pair<comp<ll>,int> parsed;

parsed equation(string str, int p = 0);
parsed factor(string str, int p = 0);
parsed term(string str, int p = 0);

bool overflow = false;

comp<ll> conv(string str) {
    ll val1 = 0, val2 = 0;
    for (int i = 0; i < str.size(); ++i) {
        if (str[i] != 'i') {
            val1 = val1 * 10 + (str[i] - '0');
            
            if (!isvalid(val1) || !isvalid(val2)) overflow = true;
        }
        else {
            val1 = 0;
            val2 = val1;
            break;
        }
    }
    if (str == "i") val2 = 1;
    
    if (!isvalid(val1) || !isvalid(val2)) overflow = true;
    
    return comp<ll>(val1, val2);
}

parsed equation(string str, int p) {
    parsed res = factor(str, p);
    
    if (!isvalid(res.first)) overflow = true;
    
    while (str[res.second] == '+' || str[res.second] == '-') {
        parsed temp = factor(str, res.second+1);
        
        if (!isvalid(temp.first)) overflow = true;
        
        if (str[res.second] == '+') res.first = res.first + temp.first;
        else if (str[res.second] == '-') res.first = res.first - temp.first;
        res.second = temp.second;
        
        if (!isvalid(res.first)) overflow = true;
    }
    return res;
}

parsed factor(string str, int p) {
    parsed res = term(str, p);
    
    if (!isvalid(res.first)) overflow = true;
    
    while (str[res.second] == '*' || str[res.second] == '/') {
        parsed temp = term(str, res.second+1);
        
        if (!isvalid(temp.first)) overflow = true;
        
        if (str[res.second] == '*') res.first = res.first * temp.first;
        //else if (str[res.second] == '/') res.first = res.first / temp.first;
        res.second = temp.second;
        
        if (!isvalid(res.first)) overflow = true;
    }
    return res;
}

parsed term(string str, int p) {
    if (str[p] == '(') {
        parsed res = equation(str, p+1);
        res.second += 1;
            
        if (!isvalid(res.first)) overflow = true;
        
        return res;
    }
    else {
        string snum = "";
        if (p < str.size()) {
            while (isdigit(str[p]) || str[p] == 'i') {
                snum += str[p++];
            }
        }
        comp<ll> num = conv(snum);
            
        if (!isvalid(num)) overflow = true;
        
        return parsed(num, p);
    }
}


int main() {
    //freopen( "/Users/macuser/Documents/Programming/Contest/input.in", "r", stdin );
  
    string str;
    while (cin >> str) {
        overflow = false;
        parsed res = equation(str);
        if (!overflow) {
            if (res.first.x == 0 && res.first.y == 0) cout << "0";
            if (res.first.x != 0) cout << res.first.x;
            
            if (res.first.x != 0 && res.first.y > 0) cout << "+" << res.first.y << "i" << endl;
            else if (res.first.x == 0 && res.first.y > 0) cout << res.first.y << "i" << endl;
            else if (res.first.y < 0) cout << res.first.y << "i" << endl;
            else cout << endl;
        }
        else cout << "overflow" << endl;
    }
    
    return 0;
}


Measured memory_bytes: 1232