#include<bits/stdc++.h>
#define N 100010
using namespace std;
double x,y;
int a,b,qz[100010],dl[100010],h,t,cz[100010];
int ans[N],an;
int main(){
	cin>>x>>y; x*=100000,y*=100000;
	a=x,b=y;
	for(int i=0; i<=100000; ++i)qz[i]=-2;
	qz[a]=-1; dl[1]=a; h=t=1;
	while(h<=t){
		int x=dl[h++];
		int s1=1ll*x/2;
		if(qz[s1]==-2){qz[s1]=x; cz[s1]=1; dl[++t]=s1;}
		int s2=s1+50000;
		if(qz[s2]==-2){qz[s2]=x; cz[s2]=2; dl[++t]=s2;}
	}
	for(int i=max(0,b-9); i<=min(100000,b+9); ++i){
		if(qz[i]!=-2){
			int x=i;
			while(x!=a){
				ans[++an]=cz[x];
				x=qz[x];
			}
			for(int j=an; j>=1; --j)cout<<ans[j]; return 0; 
		}
	} cout<<"F";
}