C :

#include<stdio.h>
int main()
{   
    long long i,n,a[90];
    while(scanf("%lld",&n)!=EOF)
	{ 
		a[0]=1;
		a[1]=1;
		for(i=2;i<=n;i++)
			a[i]=a[i-1]+a[i-2];
		printf("%lld\n",a[n]);
	}   
  return 0;
}

C++ :

#include<stdio.h>

int main()
{
	int n,i;
	long long a[90]={0,1,2};
	for(i=3;i<90;i++)
		a[i]=a[i-1]+a[i-2];
	while(scanf("%d",&n)!=EOF)
		printf("%lld\n",a[n]);
	return 0;
}

Pascal :

var a,b,d,c,e,i:int64;
begin
while not eof do
  begin
b:=1;
c:=2;
e:=3;
readln(a);
if a=1 then
  writeln(b);
if a=2 then
  writeln(c);
if a=3 then
  writeln(e);
if a>3 then
  begin
for i:= 3 to a do
  begin
  d:=c+b;
b:=c;
c:=d;
end;
writeln(d);
end;
end;
end.

Java :

public class Main {
            public static void main(String[] args) { 
              java.util.Scanner in= new java.util.Scanner(System.in) ;
            while(in.hasNextLong()){
            long n =in.nextLong();
              long f0=1;
              long f1=2;
              for(int i=0;i<n-2;i++){
                long a=f1;
                f1=f0+f1;
                f0=a;
              }
              if(n==1) System.out.println(f0);
              else System.out.println(f1);
            }
            }
}