#include <bits/stdc++.h>

using i64 = long long;

int main() {
    std::ios::sync_with_stdio(false);
    std::cin.tie(nullptr);
    
    std::string s;
    std::cin >> s;
    
    for (int i = 0; i < s.size() - 1; i++) {
        if (s[i] == 'O' && s[i + 1] == 'O') {
            std::cout << "INVALID\n";
            return 0;
        }
    }
    if (s.back() == 'E') {
        std::cout << "INVALID\n";
        return 0;
    }
    
    auto check = [&](i64 n) {
        for (auto x : s) {
            if (!(n & (n - 1))) {
                return false;
            }
            if ((x == 'E') != (n % 2 == 0)) {
                return false;
            }
            if (n % 2 == 0) {
                n /= 2;
            } else {
                n = 3 * n + 1;
            }
        }
        return true;
    };
    
    i64 k = 1, b = 0, d = 1;
    for (auto x : s) {
        if (x == 'O') {
            k *= 3;
            b *= 3;
            b += d;
        } else {
            d *= 2;
        }
    }
    i64 p = 4;
    while (true) {
        i64 n = p * d - b;
        if (n > 0 && n % k == 0) {
            n /= k;
            if (check(n)) {
                std::cout << n << "\n";
                return 0;
            }
        }
        p *= 2;
    }
    
    return 0;
}