#include<iostream>
#include<cstring>
using namespace std;
int n,m,i,j,a[500],b[500],c[500];
int main()
{
cin>>n>>m;
a[0]=1;
a[1]=1;
memset(b,0,sizeof(b));
b[0]=1;
b[1]=0;
for (j=2;j<=m-n+1;j++)
{
for (i=0;i<=a[0];i++) c[i]=a[i];
for (i=1;i<=a[0];i++)
{
a[i]+=b[i];
a[i+1]+=a[i]/10;
a[i]%=10;
}
while (a[a[0]+1]>0) a[0]++;
// memset(b,0,sizeof(b));
for (i=0;i<=c[0];i++) b[i]=c[i];
}
for (i=a[0];i>=1;i--) cout<<a[i];
cout<<endl;
return 0;
}