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

#define x(k) (((k) >= 0) ? in[strlen(in) - 1 - (k)] - '0' : 0)
void esr(char *in, char *out, int len)
{
  int n, i, a, r, q, z, t;
  char *p;

  p = out;
  n = ((len - 1) / 2) * 2;
  r = 0;
  q = 0;
  a = 0;
  z = 10 * x(n + 1) + x(n);
  i = n - 1;
  
  do {
    for(a = 0; a <= 9; a++) {
      if ((10 * q + a) * a <= z && z < (10 * q + (a + 1)) * (a + 1))
        break;
    }
    if (i == -3)
      *p++ = '.';
    *p++ = a + '0';
    r = (10 * q + a) * a;
    q = 10 * q + 2 * a;
    z = 100 * (z - r) + 10 * x(i);
    i--;
    z = z + x(i);
    i--;
  } while (i >= -3);
  *p = '\0';
  return;
}

#define N 8
int main()
{
  static char in[N + 1], out[N];
  int n;
  char *p;

  printf(">");
  fgets(in + 1, N, stdin);
  in[0] = '0';
  for (p = in; *p != '\n'; p++);
  *p = '\0';
  n = strlen(in + 1);

  if (n % 2 == 0)
    esr(in + 1, out, n);
  else
    esr(in, out, n);

  printf("%s\n", out, n);
  return 0;
}
/* end */