#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using LL = long long;
using pii = pair<int, int>;
#define sz(x) signed(size(x))

void solve() {
    string s;
    cin >> s;

    if (s == "") {
        cout << 2 << '\n';
        return;
    }

    int n = sz(s);
    for (int i = 1; i < n; ++i)
        if (s[i - 1] == 'O' && s[i] == 'O') {
            cout << "INVALID\n";
            return;
        }

    if (s.back() != 'O') {
        cout << "INVALID\n";
        return;
    }

    vector<unsigned __int128> two(127, 1);

    for (int i = 1; i < 127; ++i)
        two[i] = two[i - 1] * 2;
    set<unsigned __int128> st(two.begin(), two.end());

    ll ans = -1;
    reverse(s.begin(), s.end());
    for(int i = 1;i <= 64;i ++){
        unsigned __int128 cur = two[i];
        int f = 1;
        for(char c : s){
            if(c == 'O'){
                cur -= 1;
                if(cur % 3){
                    f = 0;
                    break;
                }
                cur /= 3;
                if(cur % 2 == 0){
                    f = 0;
                    break;
                }
            } else {
                cur *= 2;
            }

            if (st.count(cur)) {
                f = 0;
                break;
            }
        }
        if(f){
            if(ans == -1){
                ans = cur;
            } else {
                if(cur > (1ll<<47))
                    continue;
                ans = min(ans, (ll)cur);
            }
        }
    }
    cout << ans << "\n";
    return;
}

signed main() {
    cin.tie(0)->sync_with_stdio(0);
    int t = 1;
    while (t--)
        solve();
    return 0;
}