C++ :

#include<iostream>
#include<cstring>
using namespace std;
long long 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=n+1;j<=m;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,sizeof(b),0);
		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;
}

Pascal :

var i,j,n,m:integer;
    b:array[0..1000,0..1000] of integer;
    l:array[0..1000]of integer;
procedure work(x,y,z:integer);
var i1,j1,l1:integer;
begin
  if l[y]>l[z] then l1:=l[y] else l1:=l[z];
  for i1:=1 to l1 do begin
    b[x,i1]:=b[y,i1]+b[z,i1]+b[x,i1];
    b[x,i1+1]:=b[x,i1] div 10;
    b[x,i1]:=b[x,i1] mod 10;
  end;
  if b[x,l1+1]>0 then l[x]:=l1+1 else l[x]:=l1;
end;
begin
  readln(n,m);
  fillchar(b,sizeof(b),0);
  b[n,1]:=1; b[n+1,1]:=1;
  l[n]:=1; l[n+1]:=1;
  for i:=n+2 to m do begin
    work(i,i-1,i-2);
  end;
  for i:=l[m] downto 1 do write(b[m,i]);
end.