#include<cstdio>
int k,n;
void citire()
{
	FILE *f = fopen("kfib.in","r");
	fscanf(f,"%d",&k);
	fclose(f);
}
void fib()
{
	int p,aux,i;
	if((k==1)||(k==2))
		n=1;
	aux=1;
	p=1;
	if(k>=3)
		for(i=3;i<=k;i++)
		{
			n=aux+p;
			p=aux;
			aux=n;
		}
}
void afisare()
{
	FILE *g = fopen("kfib.out","w");
	fprintf(g,"%d",n);
	fclose(g);
}
int main()
{
	citire();
	fib();
	afisare();
	return 0;
}