C Malloc multi dimension Dynamic allocation

#include<stdio.h>
int main()
{
    char ***p;
    int i,j,r,c;
    r = 10, c = 12;
    p = (char ***) malloc(r * sizeof(char**));
    for(i=0;i<r;i++) {
        p[i] = (char **) malloc (c * sizeof(char *));
        for(j=0;j<c;j++) {
            p[i][j] = (char *) malloc(10);
        sprintf(p[i][j],"%d:%d",i,j);
            printf("%s\t",p[i][j]);
        }
        printf("\n");
        }       

// Cleanup
    for(i=0;i<r;i++) {
        for(j=0;j<c;j++) {
            free(p[i][j]);
        }    
        free(p[i]);
    }
    free(p);
}