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