#include "mpi.h"
#include <iostream>
#include <math.h>

const int Tag = 0;
const int TagSecond = 1;
const int root = 0;

double composition_array(int begin, int end) {
    double composition = 1;
    for (int i = begin; i < end; ++i) {
        composition *= 1 + 1 / (i * log(i));
//        std::cout << 1 + 1 / (i * log(i)) << " ";
    }
//    std::cout << std::endl;
    return composition;
}
int main() {
    int rank, comm_size;
    MPI_Init(NULL, NULL);
    MPI_Comm_rank(MPI_COMM_WORLD, &rank);
    MPI_Comm_size(MPI_COMM_WORLD, &comm_size);
    double *arr;
    double composition = 1;
    double buffer;
    int part_size;
    int begin, end;
    int n;
    MPI_Status status;
    if (root == rank) {
        std::cout << "n : ";
        std::cin >> n;
        n -= 1;
        part_size = n / comm_size;
        for (int i = root + 1; i < comm_size; ++i) {
            MPI_Send(&part_size, 1, MPI_INT, i, TagSecond, MPI_COMM_WORLD);
        }
        int shift = n % comm_size;
        int send_message;
//      std::cout << "'''''''''''''''''''''''" << std::endl;
  //      std::cout << shift << " " << part_size << std::endl;
  //      std::cout << "iiiiiiiiiiiiiiiiiiiiiiii" << std::endl;
        for (int i = root + 1; i < comm_size; ++i) {
            send_message = 2 + shift + part_size * i;
            MPI_Send(&send_message, 1, MPI_INT, i, Tag, MPI_COMM_WORLD);
        }
 //       std::cout << rank << " : ";
        composition = composition_array(2, 2 + shift + part_size);
        for (int i = root + 1; i < comm_size; ++i) {
            MPI_Recv(&buffer, 1, MPI_DOUBLE, i, Tag, MPI_COMM_WORLD, &status);
            composition *= buffer;
        }

    } else {
       // MPI_Probe(root, Tag2, MPI_COMM_WORLD, &status);
        MPI_Recv(&part_size, 1, MPI_INT, root, TagSecond, MPI_COMM_WORLD, &status);
        MPI_Recv(&begin, 1, MPI_INT, root, Tag, MPI_COMM_WORLD, &status);
       // std::cout << part_size << std::endl;
  //      std::cout << rank << " : ";
        double composition_tmp = composition_array(begin, begin + part_size);
        std::cout << begin << " " << part_size << std::endl;
        MPI_Send(&composition_tmp, 1, MPI_DOUBLE, root, Tag, MPI_COMM_WORLD);
    }

    if (rank == 0) {
        std::cout << rank << " : " << composition << std::endl;
    }
    MPI_Finalize();
    return 0;
}