#include <bits/stdc++.h>
#define pb push_back
using ll = long long;
using namespace std;

string s;

vector<ll> ans;

__int128 last;

bool dfs(__int128 x, int i){
	if(x == 0 || ((x & -x) == x && i != s.size() - 1))
		return 0;
	if(i == -1)
		return last = x, 1;
	if(s[i] == 'O'){
		if((x - 1) % 3 != 0 || ((x - 1) / 3) % 2 == 0)
			return 0;
		return dfs((x - 1) / 3, i - 1);
	}
	return dfs(x << 1, i - 1);
}

int main() {
	cin >> s;
	if(s.back() != 'O')
		return cout << "INVALID\n", 0;
	for(__int128 x = 1; x <= (__int128(1) << 60); x <<= 1){
		if(dfs(x, s.size() - 1)){
			ans.pb(last);
			break;
		}
	}
	if(ans.empty())
		cout << "INVALID\n";
	else
		cout << *min_element(ans.begin(), ans.end()) << "\n";
}