#include <stdio.h>
int fib( int n ){
    if (n <= 0) return 0;
    if (n == 1) return 1;

    int a = 0;      
    int b = 1;      
    int result = 0;
    for (int i = 2; i <= n; i++) {
        result = a + b; 
        a = b;          
        b = result;     
    }

    return result;
}
int main(void) {
int n;
scanf("%d", &n);
printf("fib(%d)=%d\n", n, fib(n));
return 0;
}