#include <iostream>
#include <ctype.h>
#include <list>

using namespace std;

class Complex Eval(const char *str,int start,int end);
int GetRightParenthesis(const char *str,int trg);

class Complex{
public :
  int x;// 
  int y;// x + y i
  Complex(int x,int y);
  void Print();
  void Add(Complex &c);
  void Sub(Complex &c);
  void Mul(Complex &c);
  bool IsOverflow();
};
class Overflow{};

Complex::Complex(int x,int y){
  this->x = x;
  this->y = y;
}

void Complex::Print(){
  if(x==0 && y==0){
    printf("0\n");
  }else if(x==0){
    printf("%di\n",y);
  }else if(y==0){
    printf("%d\n",x);
  }else{
    printf("%d%c%di\n",x,(y>0?'+':'-'),(y>0?y:-y));
  }
  
}
void Complex::Add(Complex &c){
  this->x += c.x;
  this->y += c.y; 
}
void Complex::Sub(Complex &c){
  this->x -= c.x;
  this->y -= c.y; 
}
void Complex::Mul(Complex &c){
  int tmp;
  tmp     = (this->x * c.x) - (this->y * c.y);
  this->y = (this->x * c.y) + (this->y * c.x); 
  this->x = tmp;
}
bool Complex::IsOverflow(){
  return (x<-10000 || x>10000 || y<-10000 || y>10000);
}


Complex Eval(const char *str,int start,int end){
  list<Complex *> lc; 
  list<Complex *>::iterator plc;
  list<char> lr;
  list<char>::iterator plr;
  int now,tmp;
  Complex * ptmpc;
  
  now = start;
  try{
    // パーシング
    while(now<=end){
      switch(str[now]){
      case '+':
      case '-' :
      case '*' :
	lr.push_back(str[now]);
	now++;
	break;
      case 'i' :
	lc.push_back(new Complex(0,1));
	now++;
	break;
      case '(' :
	tmp = GetRightParenthesis(str,now);
	lc.push_back(new Complex(Eval(str,now+1,tmp-1)));
	now = tmp+1;
	break;
      default : //残りは数字
	tmp = 0;
	while(now<=end && isdigit(str[now])){
	  tmp = tmp*10 + str[now] -'0';
	  now++;
	  if(tmp > 10000) throw Overflow();
	}
	lc.push_back(new Complex(tmp,0));
      }
    }
    //演算実行
    plc = lc.begin();
    plr = lr.begin();
    while(plr != lr.end()){
      if(*plr == '*'){
	ptmpc = *plc;
	plc++;
	ptmpc->Mul(**plc);
	plr = lr.erase(plr);
	lc.erase(plc);
	plc--;
	if(ptmpc->IsOverflow()) throw Overflow();
      }else{
	plr++;
	plc++;
      }
    }
    plc = lc.begin();
    plr = lr.begin();
    while(plr != lr.end()){
      ptmpc = *plc;
      plc++;
      if(*plr == '+'){
	ptmpc->Add(**plc);
      }else{
	ptmpc->Sub(**plc);
      }
      plr = lr.erase(plr);
      lc.erase(plc);
      plc--;
      if(ptmpc->IsOverflow()) throw Overflow();
    }
  
  }catch(...){
    plc = lc.begin();
    while(plc!= lc.end()){
      delete *plc;
      plc++;
    }
    throw;
  }
  Complex answer(*(lc.front()));
    plc = lc.begin();
    while(plc!= lc.end()){
      delete *plc;
      plc++;
    }
    return answer;
}
int GetRightParenthesis(const char *str,int trg){
  int lev=0;
  int now=trg;
  
  while(true){
    if(str[now]=='('){
      lev++;
    }else if(str[now]==')'){
      lev--;
      if(lev==0) return now;
    }
    now++;
  }
}



int main(void){
  char buf[128];//最大100文字までですけど。
  int end;
  Complex answer(0,0);
  
  while(fgets(buf,sizeof(buf),stdin)!=NULL){
    end = strlen(buf);
    end--;
    while(buf[end]=='\r'||buf[end]=='\n') end--;
    try{
      answer = Eval(buf,0,end);
      answer.Print();
    }catch(Overflow){
      puts("overflow");
    }
  }
  
  
}