#pragma GCC optimize ("Ofast")
#include<bits/stdc++.h>
using namespace std;
inline int my_getchar_unlocked(){
  static char buf[1048576];
  static int s = 1048576;
  static int e = 1048576;
  if(s == e && e == 1048576){
    e = fread_unlocked(buf, 1, 1048576, stdin);
    s = 0;
  }
  if(s == e){
    return EOF;
  }
  return buf[s++];
}
inline void rd(long long &x){
  int k;
  int m=0;
  x=0;
  for(;;){
    k = my_getchar_unlocked();
    if(k=='-'){
      m=1;
      break;
    }
    if('0'<=k&&k<='9'){
      x=k-'0';
      break;
    }
  }
  for(;;){
    k = my_getchar_unlocked();
    if(k<'0'||k>'9'){
      break;
    }
    x=x*10+k-'0';
  }
  if(m){
    x=-x;
  }
}
struct MY_WRITER{
  char buf[1048576];
  int s;
  int e;
  MY_WRITER(){
    s = 0;
    e = 1048576;
  }
  ~MY_WRITER(){
    if(s){
      fwrite_unlocked(buf, 1, s, stdout);
    }
  }
}
;
MY_WRITER MY_WRITER_VAR;
void my_putchar_unlocked(int a){
  if(MY_WRITER_VAR.s == MY_WRITER_VAR.e){
    fwrite_unlocked(MY_WRITER_VAR.buf, 1, MY_WRITER_VAR.s, stdout);
    MY_WRITER_VAR.s = 0;
  }
  MY_WRITER_VAR.buf[MY_WRITER_VAR.s++] = a;
}
inline void wt_L(char a){
  my_putchar_unlocked(a);
}
int WRITER_DOUBLE_DIGIT = 15;
inline int writerDigit_double(){
  return WRITER_DOUBLE_DIGIT;
}
inline void writerDigit_double(int d){
  WRITER_DOUBLE_DIGIT = d;
}
inline void wt_L(double x){
  const int d = WRITER_DOUBLE_DIGIT;
  int k;
  int r;
  double v;
  if(x!=x || (x==x+1 && x==2*x)){
    my_putchar_unlocked('E');
    my_putchar_unlocked('r');
    my_putchar_unlocked('r');
    return;
  }
  if(x < 0){
    my_putchar_unlocked('-');
    x = -x;
  }
  x += 0.5 * pow(0.1, d);
  r = 0;
  v = 1;
  while(x >= 10*v){
    v *= 10;
    r++;
  }
  while(r >= 0){
    r--;
    k = floor(x / v);
    if(k >= 10){
      k = 9;
    }
    if(k <= -1){
      k = 0;
    }
    x -= k * v;
    v *= 0.1;
    my_putchar_unlocked(k + '0');
  }
  if(d > 0){
    my_putchar_unlocked('.');
    v = 1;
    for(r=(0);r<(d);r++){
      v *= 0.1;
      k = floor(x / v);
      if(k >= 10){
        k = 9;
      }
      if(k <= -1){
        k = 0;
      }
      x -= k * v;
      my_putchar_unlocked(k + '0');
    }
  }
}
inline void wt_L(const char c[]){
  int i=0;
  for(i=0;c[i]!='\0';i++){
    my_putchar_unlocked(c[i]);
  }
}
template<class T, class U> inline T GCD_L(T a, U b){
  T r;
  while(b){
    r=a;
    a=b;
    b=r%a;
  }
  return a;
}
template<class S, class T> inline S chmax(S &a, T b){
  if(a<b){
    a=b;
  }
  return a;
}
int main(){
  long long A;
  rd(A);
  long long B;
  rd(B);
  long long i;
  long long j;
  long long g;
  double res = 0;
  if(A==0 && B==0){
    wt_L("0.25");
    wt_L('\n');
    return 0;
  }
  {
    auto Lj4PdHRW = (-A);
    auto KL2GvlyY = ( -B);
    chmax(A, Lj4PdHRW);
    chmax(B, KL2GvlyY);
  }
  g =GCD_L(A, B);
  if(A==0 || B==0){
    for(i=(1);i<(500);i+=(g)){
      res += pow(i+1, -(i+1));
    }
    res = 0;
  }
  else{
    for(i=(1);i<(500);i+=(g)){
      for(j=(1);j<(500);j+=(g)){
        if((A/g)%2 && (B/g)%2 && (i-1)%(2*g) != (j-1)%(2*g)){
          continue;
        }
        res += pow(i+j, -(i+j));
      }
    }
  }
  wt_L(res);
  wt_L('\n');
  return 0;
}
// cLay varsion 20201026-1

// --- original code ---
// {
//   ll @A, @B, i, j, g;
//   double res = 0;
// 
//   if(A==0 && B==0) wt("0.25"), return 0;
// 
//   (A, B) >?= (-A, -B);
//   g = gcd(A,B);
// 
//   if(A==0 || B==0){
//     rep(i,1,500,g) res += pow(i+1, -(i+1));
//     res = 0;
//   } else {
//     rep(i,1,500,g) rep(j,1,500,g){
//       if((A/g)%2 && (B/g)%2 && (i-1)%(2*g) != (j-1)%(2*g)) continue;
//       res += pow(i+j, -(i+j));
//     }
//   }
// 
//   wt(res);
// }