How to take matrix input dynamically with MPI - c

Question

I have written the code for matrix multiplication that takes input randomly from 1 to 9 and creates the matrix , the code is actually in MPI, the problem is that it works only for 4x4 matrix if i try anything like 5x5 or 10x10 it starts giving random values,I always change the value of N before creating any other order matrix, i don't know if its a MPI problem or just basic C programming error that I am doing, the code i have written is
#define N 4
#include <stdio.h>
#include <math.h>
#include <stdlib.h>
#include <time.h>
#include "mpi.h"
void print_results(char *prompt, int a[N][N]);
int main(int argc, char *argv[])
{
int i, j, k, rank, size, tag = 99, sum = 0;
int a[N][N];
int b[N][N];
int c[N][N];
int aa[N],cc[N];
int row,col;
int dest = 0;
int source;
double time1, time2, duration, global;
MPI_Status status;
MPI_Init(&argc, &argv);
MPI_Comm_size(MPI_COMM_WORLD, &size);
MPI_Comm_rank(MPI_COMM_WORLD, &rank);
if(rank == 0){
printf("enter the number of row =");
scanf("%d",&row);
printf("enter the number of column =");
scanf("%d",&col);
srand(time(NULL));
for(i=0;i<row;i++) {
for(j=0;j<col;j++){
a[i][j] = rand() % 10;
}
}
for(i=0;i<row;i++){
for(j=0;j<col;j++){
b[i][j] = rand() % 10;
}
}
}
MPI_Barrier(MPI_COMM_WORLD);
time1 = MPI_Wtime();
MPI_Scatter(a, N*N/size, MPI_INT, aa, N*N/size, MPI_INT,0,MPI_COMM_WORLD);
MPI_Bcast(b, N*N, MPI_INT, 0, MPI_COMM_WORLD);
MPI_Barrier(MPI_COMM_WORLD);
for (i = 0; i < N; i++)
{
for (j = 0; j < N; j++)
{
sum = sum + aa[j] * b[j][i];
}
cc[i] = sum;
sum = 0;
}
MPI_Gather(cc, N*N/size, MPI_INT, c, N*N/size, MPI_INT, 0, MPI_COMM_WORLD);
MPI_Barrier(MPI_COMM_WORLD);
time2 = MPI_Wtime();
duration = time2 - time1;
MPI_Reduce(&duration,&global,1,MPI_DOUBLE,MPI_SUM,0,MPI_COMM_WORLD);
if(rank == 0) {
printf("Global runtime is %f\n",global);
}
printf("Runtime at %d is %f \n", rank,duration);
MPI_Finalize();
if (rank == 0)
print_results("C = ", c);
}
void print_results(char *prompt, int a[N][N])
{
int i, j;
printf ("\n\n%s\n", prompt);
for (i = 0; i < N; i++) {
for (j = 0; j < N; j++) {
printf(" %d", a[i][j]);
}
printf ("\n");
}
printf ("\n\n");
}
Any solutions, please help me out with it!!