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#include <bits/stdc++.h>
using namespace std;
string s;
int dfs(int l, int r) {
    if (l > r) return 0;
    string t;
    while (l  <= r && s[l] >= 'A' && s[l] <= 'Z') {
        t += s[l];
        l++;
    }
    int num = 0;
    while(l <= r && s[l] >= '0' && s[l] <= '9') {
        num = num * 10 + s[l] - '0';
        l ++;
    }
    if(t == "FD") return num + dfs(l,r);
    else if(t == "BK") return - num + dfs(l,r);
    else{
        int ans = 0;
        for (int i = l;i <= r;i ++) {
            if(s[i] == '[') ans ++;
            else if(s[i] == ']') ans --;
            if(ans == 0) return num * dfs(l + 1,i - 1) + dfs(i + 1,r);
        }
    }
}
int main() {
    string str;
    while (cin >> str) {
        s += str;
    }
    cout << abs(dfs(0,s.size() - 1)) << endl;
    return 0;
}