//sirul lui Fibonacci
#include<stdio.h>

int main()
{
	FILE *inputFile, *outputFile;
	inputFile=fopen("kfib.in", "r");
	outputFile=fopen("kfib.out", "w");

	int n,i;
	int fib1=0, fib2=1, fib3;
	fscanf(inputFile, "%d", &n);

	if(n == 0)
		fprintf(outputFile, "%d", 0);
	if(n == 1)
		fprintf(outputFile, "%d", 1);
	for(i=3; i<=n; i++)
	{
		fib3=fib1+fib2;
		fib1=fib2;
		fib2=fib3;
	}
	fprintf(outputFile, "%d", fib3);
	return 0;
}