Simple C program that can be compiled into WebAssembly

hello.c

#include <stdio.h>
#include <emscripten.h> 

int EMSCRIPTEN_KEEPALIVE fib(int n){
    if(n == 0 || n == 1)
        return 1;
    else
        return fib(n - 1) + fib(n - 2);
}