Twenty-six people gather in a house. Alicia is friends with only one person, Bruno is friends with two people, Carlos is a friend of three, Daniel is four, Elías is five, and so following each person is friend of a person more than the previous person, until reaching Yvonne, the person number twenty-five, who is a friend to everyone. How many people is Zoila a friend of, person number twenty-six?

Clarification: If $A$ is a friend of $B$ then $B$ is a friend of $A$.
1. **Define the problem in terms of the number of friends each person has:**
   - Let \( P_n \) represent the \( n \)-th person.
   - According to the problem, \( P_1 \) has 1 friend, \( P_2 \) has 2 friends, and so on up to \( P_{25} \) who has 25 friends.
   - We need to determine the number of friends \( P_{26} \) (Zoila) has.

2. **Analyze the friendship structure:**
   - Since \( P_{25} \) is friends with everyone, \( P_1 \)'s only friend must be \( P_{25} \).
   - \( P_2 \) must be friends with \( P_{25} \) and one other person. Since \( P_1 \) already has their only friend, \( P_2 \)'s second friend must be \( P_{26} \).
   - \( P_3 \) must be friends with \( P_{25} \) and two other people. Since \( P_1 \) and \( P_2 \) already have their friends, \( P_3 \)'s additional friends must include \( P_{26} \).

3. **Continue this pattern:**
   - \( P_4 \) must be friends with \( P_{25} \) and three other people. Since \( P_1, P_2, \) and \( P_3 \) already have their friends, \( P_4 \)'s additional friends must include \( P_{26} \).
   - This pattern continues until \( P_{13} \).

4. **Determine the friends of \( P_{13} \):**
   - \( P_{13} \) must be friends with \( P_{25} \) and twelve other people.
   - Since \( P_1, P_2, \ldots, P_{12} \) already have their friends, \( P_{13} \)'s additional friends must include \( P_{26} \).

5. **Count the friends of \( P_{26} \):**
   - \( P_{26} \) must be friends with \( P_{13}, P_{14}, \ldots, P_{25} \).
   - The number of friends \( P_{26} \) has is \( 25 - 13 + 1 = 13 \).

The final answer is \( \boxed{13} \).