#include <stdio.h> 
#include <mpi.h> 
int main(int argc, char **argv) { 
  double precision=10000000; 
  //precision=100 ;
  int myrank,proccount; 
  double pi,pi_final; 
  int mine,sign, licznik, sign2; 
  int i; 
  // Initialize MPI
  MPI_Init(&argc, &argv); 
  // find out my rank
  MPI_Comm_rank(MPI_COMM_WORLD, &myrank); 
  // find out the number of processes in MPI_COMM_WORLD
  MPI_Comm_size(MPI_COMM_WORLD, &proccount); 
  // now distribute the required precision
  if (precision<proccount) { 
    printf("Precision smaller than the number of processes - try again."); 
    MPI_Finalize(); 
    return -1; 
  } 
  // each process performs computations on its part
  
  pi=0;
  licznik=0;
  mine=-1;
  //
  sign2=-1;
  
  mine+=(myrank*proccount*2)+2;
  if(proccount%2==1)
  {
    if(myrank%2==1)
    {
      sign2=1;
    }
  }
  
  for(;mine<precision;)
  {
    sign2=sign2*(-1);
    if(licznik==proccount)
    {
      licznik=0;
      mine+=((proccount-1)*(proccount)*2);
      int i2=0;
      if((proccount%2)!=0)
      {
    for(i2;i2<proccount;i2++)
    {
      //sign2=sign2*(-1);
     //printf("\nvvvvvvvvvvvvvvvv");

    }
      }
      //mine+=(2*2*(proccount+1));
    } 
    //if(myrank==2) printf("\nProcess mryank: %d sign2: %d mine: %d, procca: %d \n\n", myrank,sign2,mine, proccount);
    pi+=sign2/(double)mine; 
    mine+=2; 
    licznik++;
  }
  
  /*
  mine=myrank*2+1; 
  sign=(((mine-1)/2)%2)?-1:1; 
  for (;mine<precision;) { 
    //        printf("\nProcess %d %d %d", myrank,sign,mine);
    //        fflush(stdout);
    pi+=sign/(double)mine; 
    mine+=2*proccount; 
    sign=(((mine-1)/2)%2)?-1:1; 
  } */
  // now merge the numbers to rank 0
  MPI_Reduce(&pi,&pi_final,1, 
             MPI_DOUBLE,MPI_SUM,0, 
             MPI_COMM_WORLD); 
  if (!myrank) { 
    pi_final*=4; 
    printf("\n\n\npi=%.20f",pi_final);
   
  } 
  // Shut down MPI
  MPI_Finalize(); 
  return 0; 
}