method 2 error

void method2()
{
    int i,j;
    struct place *a;
    a=(struct place*)malloc(sizeof(struct place));

    pthread_t threads[rowSize1*colSize2]; /* descriptors of threads */
    for(i = 0; i < rowSize1; i++)  /* create threads */
    {
        for(j=0; j<colSize2; j++)
        {
            a->r=i;
            a->c=j;
            if (pthread_create(&threads[i*j], NULL, executeMethod2, (void *)a))
            {
                printf("Can not create a thread\n");
                exit(1);
            }

        }

    }
    for(i = 0; i < rowSize1; i++)  /* create threads */
    {
        for(j=0; j<colSize2; j++)
        {
            int value; /* value returned by thread */
            pthread_join(threads[i*j], (void **)&value);
            outputMatrix2[i][j]=value;
            printf("%d  ",outputMatrix2[i][j]);
        }
        printf("\n");
    }
}