#include <bits/stdc++.h>
#define int long long
#define x first
#define y second
#define pb push_back
void debug() {std::cerr << "\n";}
template<class T, class... OtherArgs>
void debug(T &&var, OtherArgs &&... args) {
    std::cerr << std::forward<T>(var) << " ";
    debug(std::forward<OtherArgs>(args)...);
}
#define SZ(x) (int)(x).size()
#define all(x) (x).begin(), (x).end()
using namespace std;
mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
typedef long long LL;
typedef long double LD;
typedef unsigned long long ULL;
typedef pair<int, int> PII;
const int N = 1010, M = 10000010;
const int P = 998244353;
LL powmod(LL a, LL b, LL p = P) {LL res = 1 % p; a %= p; assert(b >= 0); for(; b; b >>= 1) { if (b & 1) res = res * a % p; a = a * a % p; } return res; }

int n, m;

void solve() {
    string s;
    cin >> s;
    n = s.size();

    for (int i = 1; i < n; i++) {
        if (s[i] == 'O' && s[i - 1] == 'O') {
            cout << "INVALID\n";
            return;
        }
    }
    if (s.back() == 'E') {
        cout << "INVALID\n";
        return;
    }
    
    __int128 ans = 1e18;
    for (int now = 8; now <= 1ll << 47; now <<= 1) {
        __int128 x = now;
        for (int i = n - 1; ~i; i--) {
            if (s[i] == 'O') {
                if ((x - 1) % 3) {
                    x = -1;
                    break;
                }
                x = (x - 1) / 3;
            } else {
                if ((x & (x - 1)) == 0) {
                    x = -1;
                    break;
                }
                x *= 2;
            }
        }
        if (x != -1) {
            ans = min(ans, x);
        }
    } 
    cout << (int)ans << '\n';
}

signed main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    cout << fixed << setprecision(20);
    int _ = 1;
    // cin >> _;
    while (_--) solve();
}