#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define endl '\n'
int main() {
  string str;
  cin >> str;
  for (int i = 0; i < str.size(); i++) {
    if (str[i] != 'E' && str[i] != 'O') {
      cout << "INVALID" << endl;
      return 0;
    }
  }
  if (str[str.size() - 1] != 'O') {
    cout << "INVALID" << endl;
    return 0;
  }
  for (int i = 0; i < str.size() - 2; i++) {
    if (str[i] == 'O' && str[i + 1] == 'O') {
      cout << "INVALID" << endl;
      return 0;
    }
  }
  ll num = 16;
  int p = 0;
  while (1) {
    ll number = num;
    int check = 0;
    bool jud = 1;
    for (int i = str.size() - 1; i >= 0; i--) {
      if (str[i] == 'E') {
        number *= 2;
        ll pp = number;
        while (pp % 2 == 0 && pp != 0)
          pp /= 2;
        if (pp == 0)
          check = 1;
      } else if (str[i] == 'O') {
        if ((number - 1) % 3 == 0) {
          number = (number - 1) / 3;
          if (number == 1)
            check = 0;
        } else {
          jud = 0;
          break;
        }
      }
    }
    if (check) {
      num *= 2;
      p++;
      continue;
    }
    if (jud) {
      cout << number << endl;
      break;
    }
    num *= 2;
    p++;
    if (p > 70) {
      cout << "INVALID" << endl;
      break;
    }
  }
  return 0;
}