// compute DFT magnitude from input samples

#include <stdio.h>
#include <stdlib.h>
#include <math.h>

// #define N 256
// #define N2 ((N/2)+1)

int main( void)
{
  int N;

  if( scanf( "%i", &N) != 1) return 1;

  int N2 = (N/2)+1;

  double C[N2], S[N2], pi = 4*atan(1), x, wk;

  int s, j, k = 0;

  for( j = 0; j < N2; ++j) C[j] = S[j] = 0;

  while(1)
  {
    s = scanf( "%lf", &x); if( s != 1) break;

    for( j = 0; j < N2; ++j)
    {
      wk = (2*pi*j/N)*k;
      C[j] += x*cos(wk);
      S[j] += x*sin(wk);
    }
    ++k;
  }

// skip DC 
  for( j = 1; j < N2; ++j)
    printf( "%i %g\n", j, sqrt(C[j]*C[j]+S[j]*S[j]) );

  return 0;
}