I have a problem with using scatter in mpi

this is my code I have a matrix n*m when the process id is 0 I enter the n and m and put values in arr the broadcast n and m to other process and I use scatter to divide the matrix on them and I recive the value of matrix in temp arr and I don’t know if arr has a garbage value or temp don’t recive the values it shoud find the max value in the matrix

#include <mpi.h>
#include <iostream>
#include <unistd.h>
#include <string>
#include <math.h>
#include <chrono>


using namespace std;
using namespace chrono;



int main(int argc, char **argv) {
     int id, np;
    MPI_Status status;
    MPI_Init(&argc, &argv);
    MPI_Comm_rank(MPI_COMM_WORLD, &id); // return the id of the process
    MPI_Comm_size(MPI_COMM_WORLD, &np); // return the number of processes
    int n, m;
    int **arr;
    int **temp;
    if(id == 0) {
        printf("enter n and mn");
        cin >> n >> m;

        arr = new int*[n];
        for(int i = 0; i < n; i++) {
            arr[i] = new int[m];
        }

        for(int i = 0; i < n; i++) {
            for(int j = 0; j < m; j++) {
                arr[i][j] = i + j;
            }
        }
    }

    MPI_Bcast(&n, 1, MPI_INT, 0, MPI_COMM_WORLD);
    MPI_Bcast(&m, 1, MPI_INT, 0, MPI_COMM_WORLD);
    MPI_Barrier(MPI_COMM_WORLD);

    temp = new int*[n/np];
    for(int i = 0; i < n/np; i++) {
        temp[i] = new int[m];
    }
    MPI_Barrier(MPI_COMM_WORLD);

    MPI_Scatter(&arr, (n/np) * m, MPI_INT, &temp[0][0], (n/np) * m, MPI_INT, 0, MPI_COMM_WORLD);
    MPI_Barrier(MPI_COMM_WORLD);
    printf("temp from id %d n-> %d  m->%d n", id,n,m);
    for(int i = 0; i < n/np; i++) {
        for(int j = 0; j < m; j++) {
            printf(" %d ", temp[i][j]);
        }
        printf("n");
    }
    printf("n");
    
    MPI_Barrier(MPI_COMM_WORLD);
    int mx = -1;
    for(int i = 0; i < n/np; i++) {
        for(int j = 0; j < m; j++) {
            mx = max(mx, temp[i][j]);
        }
    }
    int ans;
    MPI_Reduce ( &mx, &ans, 1, MPI_INT, MPI_MAX, 0,  MPI_COMM_WORLD );

    MPI_Barrier(MPI_COMM_WORLD);
    
    if(id == 0) {
        printf("the max is %dn", ans);
    }


    return 0;
}