typedef struct {
    long x;
    long y;
    long *array;
    long length;
} foo;

long sum1(foo arg) {
    long ans = arg.x;
    for(long i = 0; i < arg.length; i += 1)
        ans += arg.y * arg.array[i];
    return ans;
}

long sum2(foo *arg) {
    long ans = arg->x;    // means same as      long ans = (*arg).x;
    for(long i = 0; i < arg->length; i += 1)
        ans += arg->y * arg->array[i];
    return ans;
}