#include <cstdio>
#include <cmath>

#define FOR( i, l, r) for(int i = (l)    ; i <  (r); i++)
#define FOR1(i, l, r) for(int i = (l)    ; i <= (r); i++)
#define REV( i, l, r) for(int i = (r) - 1; i >= (l); i--)
#define REV1(i, l, r) for(int i = (r)    ; i >= (l); i--)
#define INC( i, n) FOR( i, 0, n)
#define INC1(i, n) FOR1(i, 1, n)
#define DEC( i, n) REV( i, 0, n)
#define DEC1(i, n) REV1(i, 1, n)

typedef   signed long long int LL;
typedef unsigned long long int UL;

template<typename T> void swap(T &x, T &y) { T t = x; x = y; y = t; return; }
template<typename T> T abs(T x) { return (x > 0 ? x : -x); }
template<typename T> T max(T a, T b) { return (a > b ? a : b); }
template<typename T> T min(T a, T b) { return (a < b ? a : b); }
template<typename T> bool setmin(T &a, T b) { if(a <= b) { return false; } else { a = b; return true; } }
template<typename T> bool setmax(T &a, T b) { if(a >= b) { return false; } else { a = b; return true; } }
template<typename T> T gcd(T a, T b) { return (b == 0 ? a : gcd(b, a % b)); }
template<typename T> T lcm(T a, T b) { return a / gcd(a, b) * b; }

// ---- ----

int p0, q;
double r[101], temp[101], ans;

int main() {
	scanf("%d%d", &p0, &q);
	
	ans  += 1.0 / 3.0;
	r[p0] = 1.0 / 3.0;
	
	INC(i, 24) {
		INC(p, 101) { temp[p] = 0.0; }
		INC(p, 101) {
			double pp = p / 100.0;
			ans += r[p] * (pp / 2.0 + (1.0 - pp) / 3.0);
			
			int up = min(p + q, 100);
			int dp = max(p - q, 0);
			temp[up] += r[p] * (1.0 - pp) / 3.0;
			temp[dp] += r[p] * pp / 2.0;
		}
		INC(p, 101) { r[p] = temp[p]; }
	}
	
	printf("%.8lf\n", ans);
	
	return 0;
}