#include <bits/stdc++.h>
#define syosu(x) fixed<<setprecision(x)
using namespace std;
typedef long long ll;
typedef unsigned int uint;
typedef unsigned long long ull;
typedef pair<int,int> P;
typedef pair<double,double> pdd;
typedef pair<ll,ll> pll;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<double> vd;
typedef vector<vd> vvd;
typedef vector<ll> vl;
typedef vector<vl> vvl;
typedef vector<string> vs;
typedef vector<P> vp;
typedef vector<vp> vvp;
typedef vector<pll> vpll;
typedef pair<int,P> pip;
typedef vector<pip> vip;
const int inf=1<<30;
const ll INF=1ll<<60;
const double pi=acos(-1);
const double eps=1e-11;
const ll mod=1e9+7;
const int dx[4]={-1,0,1,0},dy[4]={0,-1,0,1};

int n;
vs a;

ll dfs(int id,int d){
	if(isdigit(a[id][d])) return a[id][d]-'0';
	char c=a[id][d];
	ll x=(c=='+'?0:1);
	for(int i=id+1;i<n&&d<a[i].size()&&a[i][d]=='.';i++) if(d+1<a[i].size()&&a[i][d+1]!='.'){
		ll y=dfs(i,d+1);
		if(c=='+') x+=y;
		else x*=y;
	}
	return x;
}

int main(){
	ios::sync_with_stdio(0);
	cin.tie(0);
	while(1){
		cin>>n;
		if(n==0) break;
		a=vs(n);
		for(int i=0;i<n;i++) cin>>a[i];
		cout<<dfs(0,0)<<endl;
	}
}
