Here's the corrected and formatted code for the add function:

```c
long int add(long int a, long int b) {
    long int sum = 0;
    long int k = 1;
    int c = 0;

    while (a || b || c) {
        sum += k * (c - c % BASE) / BASE;
        c = a % 10 + b % 10;
        sum += c % BASE * k;

        if (sum >= BASE * k) {
            c = 1;
            sum -= BASE * k;
        }

        k *= 10;
        a /= 10;
        b /= 10;
    }

    return sum;
}
```
This version of the function sets the carry variable `c` to 1 instead of 5, which should correctly handle carry values in a base number system.
spam fails_task lang_mismatch pii not_appropriate hate_speech sexual_content quality toxicity humor helpfulness creativity violence