To install MPI on Ubuntu:

https://jetcracker.wordpress.com/2012/03/01/how-to-install-mpi-in-ubuntu/

To compile mpi lab:

mpicc mpi_lab3.c -o mpi_lab3 -std=c99

To run:

mpirun -np 5 ./mpi_lab3

To compile OpenMP:

gcc lab3omp.c -o ./lab3omp -fopenmp