#define?N?50
void?Fibonacci(int?a[])
{
int?i;
a[0]?=?a[1]?=?1;
for(i?=?2;?i?<?N;?++i)
a[i]?=?a[i-1]+a[i-2];
}
int?main()
{
int?m,?k,?a[N];
int?sum?=?0;
Fibonacci(a);
scanf("%d?%d",?&m,?&k);
for(m=m-1;?m<k;?++m)
sum?+=?a[m];
printf("%d\n",?sum);
return?0;
}