#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <mpi.h>

int main(int argc, char **argv)
{
        int myrank;
        int comm_size;
        int message;
        int number;
        MPI_Status status;
        MPI_Init(&argc, &argv);
        sleep(5);
        MPI_Comm_rank(MPI_COMM_WORLD, &myrank);
        MPI_Comm_size(MPI_COMM_WORLD, &comm_size);

        int cs = comm_size-1;

        if(myrank==0)
        {
                number = 27;
                printf("Process %d: Sending number %d to process %d.\n", myrank, number, (myrank+1)%comm_size);
                MPI_Send(&number, 1, MPI_INT, (myrank+1)%comm_size, 0, MPI_COMM_WORLD);
                printf("Process %d: Number %d sent to process %d. Awaiting number from process %d.\n", myrank, number, (myrank+1)%comm_size, cs);
                MPI_Recv(&number, 1, MPI_INT, cs, MPI_ANY_TAG, MPI_COMM_WORLD, &status);
                printf("Process %d: Number %d received from process %d. Finalizing...\n", myrank, number, cs);
        }
        else
        {
                int next = (myrank+1)%comm_size;
                printf("Process %d: Awaiting a number from process %d.\n", myrank, myrank-1);
                MPI_Recv(&number, 1, MPI_INT, myrank-1, MPI_ANY_TAG, MPI_COMM_WORLD, &status);

                printf("Process %d: Number %d received from process %d. Adding %d to it...\n", myrank, number, myrank-1, 10-myrank);
                number = number + (10-myrank);

                printf("Process %d: Resulting number: %d. Sending to process %d.\n", myrank, number, next);
                MPI_Send(&number, 1, MPI_INT, next, 0, MPI_COMM_WORLD);
                printf("Process %d: Number sent to process %d.\n", myrank, next);

        }
        MPI_Finalize();
        return 0;
}