#include <bits/stdc++.h>
using namespace std;

const int MAXEND = 100;

int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);

  string s;
  cin >> s;

  bool valid = true;
  if (s[s.length() - 1] != 'O') {
    valid = false;
  }
  for (int i = 0; i < s.length(); i++) {
    if (s[i] != 'E' && s[i] != 'O') {
      valid = false;
      break;
    }
    if (i > 0 && s[i] == 'O' && s[i - 1] == 'O') {
      valid = false;
      break;
    }
  }

  if (!valid) {
    cout << "INVALID" << endl;
  } else {
    __uint128_t pow2[128];
    pow2[0] = 1;
    for (int i = 1; i < 128; i++) {
      pow2[i] = pow2[i - 1] << 1;
    }

    __uint64_t start = 0;
    for (int i = 4; i < MAXEND; i++) {
      __uint128_t cur = pow2[i];
      bool works = true;
      for (int j = s.length() - 1; j >= 0; j--) {
	if (s[j] == 'O') {
	  if ((cur - 1) % 3 != 0) {
	    works = false;
	    break;
	  }
	  cur = (cur - 1) / 3;
	  if (cur == 1 || cur % 2 == 0) {
	    works = false;
	    break;
	  }
	} else {
	  cur *= 2;
	  if (cur > pow2[MAXEND]) {
	    works = false;
	    break;
	  }
	}
      }
      if (works) {
	start = cur;
	break;
      }
    }
    if (start == 0) {
      cout << "INVALID" << endl;
    } else {
      cout << start << endl;
    }
  }
}