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

typedef __int128 ll;
ll INF=1e18;

string str;
int L;

ll check(ll ed){
	ll now=ed;
	for (int i=L-1;i>=0;i--){
		if (str[i]=='O'){
			if (now<=0 || (now-1)%3!=0) return -1;
			now=(now-1)/3;
		}
		else{
			now=now*2;	
		}
	}
	ll ans=now;
	for (int i=0;i<L;i++){
		if (str[i]=='O'){
			if (now%2==0) return -1;
			if (now==1) return -1;
			now=now*3+1; 
		}
		else{
			if (now%2==1) return -1;
			ll lb=now&(-now);
			if (now==lb) return -1;
			now=now/2;
		}
	}
	if (now==ed) return ans;
	return -1;
}

int main(){
	ios_base::sync_with_stdio(false);
	cin >> str;
	L=str.length();
	
	ll ans=INF;
	for (int i=0;i<70;i++){
		ll tmp=check(((__int128)1)<<i);
		if (tmp!=-1) ans=min(ans,tmp);
	}
	if (ans==INF) cout << "INVALID" << "\n";
	else cout << (long long)ans << "\n";
	return 0;	
}