#include <bits/stdc++.h>   const int MOD = (int)1e9 + 7;   using namespace std;   stack<long long> st;   int main() {     long long n, num;     cin >> n;     long long sum = 0;     int over = 0;     st.push(1);     for (int i = 1; i <= n; i++) {       string s;       cin >> s;       if (over == 1) continue;       if (s[0] ==  a ) {         sum += st.top();         if (sum > 4294967295) {           over = 1;         }       } else if (s[0] ==  f ) {         cin >> num;         long long f = st.top();         if (st.top() > 4294967295)           st.push(st.top());         else           st.push(f * num);       } else {         st.pop();       }     }     if (over == 1)       cout <<  OVERFLOW!!!  << endl;     else       cout << sum << endl;     return 0;   }   