#include <iostream>
#include <cstring>
#include <string>
#include <vector>
#include <algorithm>
#include <tuple>
#include <queue>
#include <set>
#include <cstdio>
#include <climits>
#include <cmath>
#include <array>
#include <functional>
#include <sstream>
#include <list>
#include <iomanip>
#include <set>
const int MOD=1000000007;
const int INF=1000000000;
using namespace std;
typedef long long ll;
typedef vector<int> vi;
const double eps=1e-9;
const int inf=1e9;
typedef pair<int,int> P;
struct Point
{
  double x,y;
  Point(){x=0;y=0;}
  Point(double d_x,double d_y){x=d_x,y=d_y;}
  double operator*(Point obj){return obj.x*x+obj.y*y;}
  double operator%(Point obj){return obj.y*x-obj.x*y;}
  Point operator*(double b){Point tmp;tmp.x=x*b;tmp.y=y*b;return tmp;}
  Point operator/(double b){Point tmp;tmp.x=x/b;tmp.y=y/b;return tmp;}
  Point operator+(Point obj){Point tmp;tmp.x=x+obj.x;tmp.y=y+obj.y;return tmp;}
  Point operator-(){Point tmp;tmp.x=-x;tmp.y=-y;return tmp;}
  Point operator-(Point obj){Point tmp;tmp.x=x-obj.x;tmp.y=y-obj.y;return tmp;}
  Point operator-=(Point obj){x-=obj.x;y-=obj.y;return *this;}
  Point operator+=(Point obj){x+=obj.x;y+=obj.y;return *this;}
  Point operator/=(double b){x=x/b;y=y/b;return *this;}
  Point operator*=(double b){x=x*b;y=y*b;return *this;}
  double size(){return hypot(x,y);}
  Point unit(){return Point(x/size(),y/size());}
  Point normal(){return Point(y,-x);}
  double atan(){return atan2(y,x);}
};

bool operator<(Point a,Point b){return a.x!=b.x?a.x<b.x:a.y<b.y;}
bool operator>(Point a,Point b){return b<a;}
bool operator<=(Point a,Point b){return !(b<a);}
bool operator>=(Point a,Point b){return !(a<b);}
bool operator==(Point a,Point b){return (a-b).size()<eps;}
bool operator!=(Point a,Point b){return !(a==b);}

bool equal(double a,double b){return abs(a-b)<eps;}
double cross(Point a,Point b){return a%b;}
double dot(Point a,Point b){return a*b;}

int ccw(Point a,Point b,Point c)
{
  b=b-a;
  c=c-a;
  if(b%c>0) return +1;
  else if(b%c<0)return -1;
  else if(b*c<0) return +2;
  else if(b.size()<c.size()) return -2;
  else return 0;
}

typedef pair<int,char> pic;
int n;
int getlevel(string &expr)
{
  int ret=0;
  while(expr[ret]=='.') ret++;
  return ret;
}

bool isdigit(char c)
{
  return c>= '0' && c<='9';
}

int process(vector<string> &expr,int* line)
{
  int ret;
  int level=getlevel(expr[*line]);
  if(level==0 && isdigit(expr[*line][level]))
    return expr[*line][level]-'0';
  else if(expr[*line][level]=='+')
    {
      (*line)++;
      ret=0;
      while((*line) < expr.size())
	{
	  int new_level=getlevel(expr[*line]);
	  if(new_level==level+1)
	    {
	      if(isdigit(expr[*line][new_level]))
		ret+=expr[*line][new_level]-'0';
	      else
		ret+=process(expr,line);
	      (*line)++;
	    }
	  else
	    {
	      (*line)--;
	      break;
	    }
	}
      return ret;
    }
  else if(expr[*line][level]=='*')
    {
      (*line)++;
      ret=1;
      while((*line)<expr.size())
	{
	  int new_level=getlevel(expr[*line]);
	  if(new_level==level+1)
	    {
	      if(isdigit(expr[*line][new_level]))
		ret*=expr[*line][new_level]-'0';
	      else
		ret*=process(expr,line);
	      (*line)++;
	    }
	  else
	    {
	      (*line)--;
	      break;
	    }
	}
      return ret;
    }
}

int main(int argc,char const* argv[])
{
  string tmp;
  while(1)
    {
      cin >> n;
      if(!n) break;
      string s;
      vector<string> expr;
      for(int i=0;i<n;i++)
	{
	  cin >> s;
	  expr.push_back(s);
	}
      int line=0;
      cout << process(expr,&line) << endl;
    }
  return 0;
}
	  



Measured memory_bytes: 3128