#define _CRT_SECURE_NO_WARNINGS 1

#include<stdio.h>

int count = 0;

int Fid(int n)

{

int a = 1;

int b = 1;

int c = 1;

while (n > 2)

{

 c = a + b;

 a = b;

 b = c;

 n--;

}

return c;

}

int main()

{

int n = 0;

scanf("%d", &n);

int ret = 0;

 ret = Fid(n);

printf("ret=%d\n", ret);

return 0;

}

//int Fac(in