Each of six people must decide whether or not to let their cows graze in a meadow.

Each of six people must decide whether or not to let their cows graze in a meadow.

The payoff to a person who doesn’tdoesn′t let her cow graze equals 0.

The payoff to a person who $does$ let her cow graze equals $4-N$, where $N$ is the number who let their cows graze.

We want the highest possible sum of payoffs to these six people. To achieve this, exactly how many people should be allowed to let their cows graze?