#include <stdio.h>
int fibonacci(int n);

int main() {
    int n;
    printf("Enter: num\nEnter: ");
    scanf("%d",&n);
    printf("fibonacci(%d) = %d",n,fibonacci(n));
    return 0;
}

int fibonacci(int n){
    if(n<=0) return 0;
    if(n==1) return 1;
    int a = 0, b = 1, next;

    for(int i = 2;i <= n;i++){
        next = a + b;
        a = b;
        b = next;
    }
    return b;
}