To load 3 C++ min, max function factors

Creating the biggest square find problem

board[i][j] = min({board[i-1][j], board[i][j-1] , board[i-1][j-1]})+1;

I don't understand the code Originally, I know that the min function brings the minimum value out of the two factors This phrase works normally

min(1,2,3);

There was an error when I wrote it like this. I don't know how to get three factors.