#include <bits/stdc++.h>
#include <unordered_map>
#include <unordered_set>
 
using namespace std;
 
#define rep(i, a, b) for(int i = a; i < (b); ++i)
#define all(x) begin(x), end(x)
#define sz(x) (int)(x).size()
typedef long long ll;
typedef pair<int, int> pii;
typedef vector<int> vi;
typedef vector<bool> vb;
typedef long double ld;
const ll mod = 1e9 + 7;
struct point {double x,y;};
typedef unsigned long long ull;
typedef pair<ll,ll> pll;
const ll inf = 1LL << 62;

ull comp(string &s, ull start) {
	for(int i = s.length()-1; i >= 0; --i) {
		if(start % 2 && s[i] == 'O') return inf;
		if(s[i] == 'O' && (start-1) % 3) return inf;
		if(s[i] == 'O') start = (start-1) / 3;
		else if(s[i] == 'E') start = 2 * start;
		if((start & (start - 1)) == 0) return inf;
	}
	return start;
}

void solve() {
	ull ans = inf;
	string s; cin >> s;
	for(ull i = 0; i < 50; ++i) {
		ull start = pow(2ll, i);
		ans = min(ans, comp(s, start));
	}
	if(ans == inf) cout << "INVALID" << endl;
	else cout << ans << endl;
}

int main() {
		//ifstream in("hps.in");
		//ofstream out("hps.out");
    //int t; cin >> t;
    //rep(i,0,t)
    solve();
}