I was stuck in this question [Your text to link here...](https://atcoder.jp/contests/agc046/tasks/agc046_b)↵
and the editorial doesn't seem to be much helpful to me .↵
However in the discussion section someone explained that this is the dp formula .↵
dp[i][j] = dp[i][j-1]*i + dp[i-1][j]*j-dp[i-1][j-1]*(i-1)*(j-1)↵
i m not able to understand how did he get the third term in the expression and more over i think this needs some correction as i was not able to get the right ans from this.
and the editorial doesn't seem to be much helpful to me .↵
However in the discussion section someone explained that this is the dp formula .↵
dp[i][j] = dp[i][j-1]*i + dp[i-1][j]*j-dp[i-1][j-1]*(i-1)*(j-1)↵
i m not able to understand how did he get the third term in the expression and more over i think this needs some correction as i was not able to get the right ans from this.
