Help me in solving RECUR05 problem

help
,
1

My issue

help me code

My code

#include <stdio.h>

int fib(int n) {

}

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

Learning course: Design and Analysis of Algorithms
Problem Link: Fibonacci Series in Design and Analysis of Algorithms