#include <iostream>

#include <iostream>
#include "stack.h"

using namespace std;

int fib(int n) {
Stack <int> s;
int sum = 0;

//first "call"
s.push(n);

while(!s.isEmpty()) {
n = s.pop();
if(n == 0 || n == 1){
sum+=1; //do something
continue;
}

//recursive cases
s.push(n-2);
s.push(n-1);
}

return sum;
}

int main(void) {
int n;
START:
cin >>n;

cout <<fib(n) << endl;
goto START;

return 0;
}