1. What I learned

    printf(), scanf()

        printf() and scanf() is faster and use less memory than cout and cin.

2. Code

#include <stdio.h>

int fib(int num) {
    if (num<2) return num;
    return (fib(num-1)+fib(num-2));
}

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

3. Result

        Runtime : 0 ms, Memory usage : 1116 KB
        (Runtime can be different by a system even if it is a same code.)

Check out the my GitHub repo for more info on the code. If you have questions, you can leave a reply on this post.