#include<bits/stdc++.h>
using namespace std;
string s;int ans,k=1;
int main(){
	getline(cin,s);
	for(int i=0;i<s.size();){
		if(s[i]==']')i++;
		if(s[i]=='F'){
			while(!isdigit(s[i]))i++;
			int ret=0;
			while(isdigit(s[i]))ret=ret*10+s[i]-'0',i++;
			ans+=k*ret;
		}
		if(s[i]=='B'){
			while(!isdigit(s[i]))i++;
			int ret=0;
			while(isdigit(s[i]))ret=ret*10+s[i]-'0',i++;
			ans-=k*ret;
		}
		if(s[i]=='R'){
			while(!isdigit(s[i]))i++;
			int ret=0;
			while(isdigit(s[i]))ret=ret*10+s[i]-'0',i++;
			k*=ret;
		}
		i++;
		
	}
	cout<<abs(ans)<<endl;
}