The problem of two balls

I think this task is not something very difficult or original, nevertheless, I am sure that many will like it. She was told by my friend, to whom his current employer, when applying for a job, offered to solve it.

There are two glass balls and a 100-story house. You throw a ball from different floors of this house in order to find out on which floor the ball begins to break from falling (for example, on the fifth it is already broken, and on the fourth one not yet). Question : what is the exact minimum number of steps needed in order to know exactly which floor the balls begin to break?

Please answer in white;)
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UPD! A step is one throw of one ball.
UPD! The ball begins to break from a certain floor.
UPD! Not everyone correctly understood the wording of the problem, so I clarify. Thank you Aleco . There are different algorithms for throwing balls to search for the number of the floor from which the ball begins to break. Each algorithm guarantees the definition of a floor for no more than N shots (for example, no more than 100, if cast consecutively starting from the lower floors). Find at least N and describe the optimal algorithm.