#include<iostream>
#include<cstdio>
#include<stack>
#include<queue>
#include<cmath>
#include<string>
#define momo 10007
using namespace std;
int n;
stack<int> sta;
int main(){
	freopen("exp.in","r",stdin);
	freopen("exp.out","w",stdout);
	cin>>n;
	string str;
	cin>>str;
	queue<char>hz;
	stack<char>ope;
	for(int i=0;i<n;++i){
		char k=str[i];
		if(k=='*' || k=='+'){
			if(i!=0 && str[i-1]==')'){
				
			}else{
				hz.push('0');
			}
			while(1){
				if(k=='*'){
					while(!ope.empty()&&ope.top()=='*'){
						hz.push(ope.top());ope.pop();
					}
					ope.push('*');
					break;
				}else if(k=='+'){
					if(!ope.empty()){
						if(ope.top()!='*'){
							ope.push(k);
						}
						break;
					}else if(ope.empty()){
						ope.push(k);
						break;
					}else{
					hz.push(ope.top());ope.pop();
					}
				}
			}
		}else if(k=='('){
			ope.push(k);
		}else if(k==')'){
			if(str[i-1]!=')'){
				hz.push('0');
			}	
			while(ope.top()!='('){
			//	cerr<<ope.top();
				hz.push(ope.top());ope.pop();
			}
			ope.pop();
		}
	}

	while(!ope.empty()){
		hz.push(ope.top());ope.pop();
	}
	//while(!hz.empty()){
	//	cout<<hz.front();hz.pop();
//	}
	stack<long>sta0;
	stack<long>sta1;
	while(!hz.empty()){
		char k=hz.front();hz.pop();
		if(k=='0'){
			sta0.push(1);
			sta1.push(1);
		}else if(k=='+'){
			long a0=sta0.top();sta0.pop();
			long b0=sta0.top();sta0.pop();
			long a1=sta1.top();sta1.pop();
			long b1=sta1.top();sta1.pop();
			sta0.push(a0*b0);
			sta1.push(a0*b1+a1*b0+a1*b1);
		}else if(k=='*'){
			long a0=sta0.top();sta0.pop();
			long b0=sta0.top();sta0.pop();
			long a1=sta1.top();sta1.pop();
			long b1=sta1.top();sta1.pop();
			sta0.push(a0*b0+a1*b0+a0*b1);
			sta1.push(a1*b1);
		}
	}
	cout<<sta0.top()<<endl;
	return 0;	
	
}