People At Party

You are at a party of $N$ people, where only one person is known to everyone. Such a person $\text{may be present}$ in the party, if yes, (s)he doesn’t know anyone at the party. Your task is to find the $stranger (guest)$ at the party. You will be given a square matrix $M$ where if an element of row $i$ and column $j$ is set to 1 it means the ith person knows the jth person. You need to fin