#include #include #include #include #include #include #include #include #include #include #include #include #include #include #pragma region using namespace std; #define FOR(i,r,n) for(ll i = (ll)(r); i < (ll)(n); i++) #define rep(i,n) FOR(i,0LL,n) #define RFOR(i,r,n) for(ll i=(ll)(n-1);i>=r;i--) #define rrep(i,n) RFOR(i,0LL,n) #define all(x) x.begin(),x.end() #define rall(x) x.rbegin(),x.rend() #define COUNT(a,y,x) upper_bound(all(a), y) - lower_bound(all(a), x) #define UNIQUE(a) sort(all(a)); a.erase(unique(all(a)), a.end()) #define pb push_back typedef long long int ll; typedef vector vll; typedef vector vvll; typedef pair pll; typedef vector vpll; typedef vector vs; typedef map MAP; const ll inf = 2222222222222222222LL; const ll mod = 1000000007LL; ll n = 0, m = 0, ans = 0, tmp = 0, ma = -inf, mi = inf; string s; bool ok; ll dx[9] = { 0,1,-1,0,0,1,1,-1,-1 }, dy[9] = { 0,0,0,1,-1,1,-1,1,-1 }; #define endl '\n' #pragma endregion #define MAX 222222 long double prob[1111][1111][2]; int main(void) { ios::sync_with_stdio(false); cin.tie(0); cin >> n; long double p, q, r; cin >> p; cin >> q; prob[0][1][0] = 1; rep(i, n) { prob[i + 1][0][1] = prob[i][0][1]; FOR(j, 1, n + 1) { prob[i + 1][j + 1][0] += prob[i][j][0] * q; prob[i + 1][j - 1][1] += prob[i][j][1] * q; prob[i + 1][j - 1][1] += prob[i][j][0] * p; prob[i + 1][j + 1][0] += prob[i][j][1] * p; } } cout.precision(18); cout << fixed << prob[n][0][1] + prob[n][0][1] << endl; return 0; }