Calculate A+B

Two men are waiting at the gates of heaven and strike up a conversation.
"How'd you die?" the first man asks the second.
"I froze to death," says the second.
"That's awful," says the first man. "How does it feel to freeze to death?"
"It's very uncomfortable at first," says the second man. "You get the shakes, and you get pains in all your fingers and toes. But eventually, it's a very calm way to go. You get numb and you kind of drift off, as if you're sleeping. How about you, how did you die?"
"I had a heart attack," says the first man. "You see, I knew my wife was cheating on me, so one day I showed up at home unexpectedly but found her alone watching television. I ran around the house looking for her lover but could find no one. As I ran up the stairs to the attic, I had a massive heart attack and died."
The second man shakes his head. "That's so ironic," he says.
"What do you mean?" asks the first man.
"If you had only stopped to look in the freezer, we'd both still be alive."