factoriel for my baby

#include <stdio.h>

int main()
{

    int n,m;
    int i,j;
    int mat[50][50];
    int f[50][50];
    /*write a program that fills a matrix of integers
    M of size ( n*m) and then calculates the sum and product
    of each column and puts it in respective arrays S and P*/

    printf("donner les dimension :\t");
    scanf ("%d %d",&n,&m);


    for (i=0; i<n; i++)
    {
        for (j=0; j<m; j++)
        {
            printf("mat[%d][%d] : ",i,j);
            scanf("%d",&mat[i][j]);
        }
    }


    printf("**Matrice donnée**:\n");
    for (i=0; i<n; i++)
    {
        for (j=0; j<m; j++)
        {
            printf("%d ",mat[i][j]);
        }
        printf("\n");
    }

    printf("**Matrice Factorielle**:\n");
    for( i=0;i<n;i++){
        for(j=0;j<m;j++){
                //boucle hedhi te7seb el factoriel
                f[i][j]=1;
                for (int a=mat[i][j];a>0;a--){
                    f[i][j]=a*f[i][j];
                }
                printf("%d\t",f[i][j]);
        }
        printf("\n");
    }


}