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Given $n$ balls. Among them, $n-1$ have the same weight, and one ball is heavier than the others. Determine the minimum number of weighings on a two-pan balance (without weights) required to find the heavy ball.

We are excited to announce new Weekend Practice round happening on Sunday, March 29, 2026 at 08:00 UTC. This is rated competition for everyone.

We are excited to announce new Blitz Round happening on Sunday, March 22, 2026 at 11:00 UTC. This is a rated competition for participants whose rating is less than or equal to 1750.

We are excited to announce 9-th Education round starting on Monday, March 16. This round is based on the problems from the archieve. This is not a rated contest but it is a good opportunity to practice tasks of varying difficulty.

We are excited to announce new Weekend Practice round happening on Sunday, March 15 at 15:00 UTC. This is rated competition for everyone.

We are excited to announce new Blitz Round happening on March 8, 2026 at 11:00 UTC. This is a rated competition for participants whose rating is less than or equal to 1750.

We are excited to announce new Blitz Round happening on Sunday, March 1, 2026 at 13:00 UTC. This is rated competition for participants whose rating is less or equal 1750.

We are excited to announce a new Blitz Round happening on February 22, 2026. This is a rated competition for participants with rating $\le 1750$.

A store offers an assortment of toys of various types. For each type, the number of toys and the price of one toy are known. Determine the total number of toys with a price less than $50$ hryvnias.

We are excited to announce new Weekend Practice round happening on Sunday, February 15, 2026. This is rated competition for everyone.

We are excited to announce 8-th Education round starting on Monday, February 9. This round is based on the problems from the archieve. This is not a rated contest but it is a good opportunity to practice tasks of varying difficulty.

We are excited to announce new Blitz Round happening on February 8, 2026 at 11:30 UTC. This is rated competition for participants with rating $\le 1750$.

A number is called massive if it can be written in the form $a^n$, that is, $a$ raised to the power of $n$.

We are excited to announce a new Weekend Practice round happening on February 1, 2026 at 15:00 UTC. This is a rated competition for everyone.

We are excited to announce new Blitz Round happening on January 25, 2026 at 13:00 UTC. This is rated competition for participants whose rating is less or equal 1750.

For the celebration, the Professor bought balloons of three colors: blue, red, and yellow. In total, he bought $n$ balloons. The number of yellow and blue balloons is $a$, and the number of red and blue balloons is $b$.

We are excited to announce new Weekend Practice round happening on January 18, 2026 at 15:00 UTC. This is rated competition for everyone.

We are excited to announce a new Blitz Round happening on January 11, 2026 at 11:00 UTC. This is a rated competition for participants with rating $\le 1750$.

We are excited to announce a new Weekend Practice round happening on Sunday, January 4 at 15:00 UTC. This is a rated competition for everyone.

Hi Eolymp Community!

We are excited to announce new Blitz Round happening on December 28, 2025 at 11:00 UTC. This is rated competition for participants whose rating is less or equal 1750.

We are excited to announce a new Weekend Practice round happening on December 21, 2025 at 15:00 UTC. This is a rated competition for everyone.

Recently, information has been spreading on the internet about our company's ties with the russian federation. We officially state: our company has no ties with the russian federation and does not cooperate with russian or pro-russian companies or websites. Our priorities are openness, integrity, honesty, and dedication to improving education in Ukraine and promoting Ukrainian worldwide.

We are excited to announce new Blitz Round happening on December 14, 2025 at 11:00 UTC. This is rated competition for participants whose rating is less or equal 1750.

We are excited to announce new Weekend Practice round happening on December 7, 2025 at 15:00 UTC. This is rated competition for everyone.