How much was the banker's bet?

The banker bet the young lawyer two million dollars that he wouldn't stay in solitary confinement for fifteen years.

"It's not true! I'll bet you two millions you wouldn't stay in solitary confinement for five years."

"If you mean that in earnest," said the young man, "I'll take the bet, but I would stay not five but fifteen years."

"Fifteen? Done!" cried the banker. "Gentlemen, I stake two millions!"

"Agreed! You stake your millions and I stake my freedom!" said the young man.