C++ :

#include<iostream>
#include<cstdlib>
const int b=1000;
long long a[b];
using namespace std;
int main()
{
	int n;
	cin>>n;
	a[1]=1;
	a[2]=1;
	a[3]=2;
	for(int i=4;i<=n;++i)
	  a[i]=a[i-1]+a[i-2];
	cout<<a[n];
	//system("pause");
	return 0;
}

Pascal :

var a:array[1..10000] of longint;
    n,i:longint;
begin
  readln(n);
  a[1]:=1; a[2]:=1;
  for i:=3 to n do
    a[i]:=a[i-1]+a[i-2];
  writeln(a[n]);
end.