Serial--> Complile: gcc -Wall pi_serial.c Run: ./a.out
MPI--> Complile: mpicc -Wall pi_mpi.c Run: mpirun -n (x) ./a.out
OpenMp->> Complile: gcc -Wall -fopenmp pi_openmp.c Run: ./a.out
MPI & OpenMP--> Complile: mpicc -Wall -fopenmp pi_mpi-openmp.c Run: mpirun -n (x) ./a.out