#include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include using namespace std; #define REP(i, n) for (int (i) = 0; (i) < (n); (i)++) #define FOR(i, a, b) for (int (i) = (a); (i) < (b); (i)++) #define RREP(i, a) for(int (i) = (a) - 1; (i) >= 0; (i)--) #define FORR(i, a, b) for(int (i) = (a) - 1; (i) >= (b); (i)--) #define DEBUG(C) cerr << #C << " = " << C << endl; using LL = long long; using VI = vector; using VVI = vector; using VL = vector; using VVL = vector; using VD = vector; using VVD = vector; using PII = pair; using PDD = pair; using PLL = pair; using VPII = vector; template using VT = vector; #define ALL(a) begin((a)), end((a)) #define RALL(a) rbegin((a)), rend((a)) #define SORT(a) sort(ALL((a))) #define RSORT(a) sort(RALL((a))) #define REVERSE(a) reverse(ALL((a))) #define MP make_pair #define FORE(a, b) for (auto &&a : (b)) #define FIND(s, e) ((s).find(e) != (s).end()) #define EB emplace_back template inline bool chmax(T &a, T b){if (a < b){a = b;return true;}return false;} template inline bool chmin(T &a, T b){if (a > b){a = b;return true;}return false;} const int INF = 1e9; const int MOD = INF + 7; const LL LLINF = 1e18; const long double EPS = 1e-9; const int MAX = 5000 * 3 + 10; long double dp[MAX], newdp[MAX]; // dp[i] = i問解いたときの平均順位 int main(void) { int N, P; int a[4]; scanf("%d%d", &N, &P); for (int i = 0; i < MAX; i++) { dp[i] = newdp[i] = INF; } dp[0] = 0; a[3] = 1; for (int i = 0; i < N; i++) { for (int j = 0; j < 3; j++) { scanf("%d", a + j); } for (int j = 0; j < MAX; j++) { for (int k = 0; k < 4; k++) { if (j + k < MAX) { chmin(newdp[j + k], (dp[j] * i + a[k]) / (i + 1)); } } } for (int j = 0; j < MAX; j++) { dp[j] = newdp[j]; newdp[j] = INF; } } printf("%.10Lf\n", dp[P]); }