inline void gauss(){int i, j, k, l;for(i = 1; i <= n; i++){l = i;for(j = i + 1; j <= n; j++)if(fabs(matrix[j][i]) > fabs(matrix[l][i])) l = j;if(l != i) for(j = i; j <= n + 1; j++)swap(matrix[i][j], matrix[l][j]);for(j = i + 1; j <= n; j++){double tmp = matrix[j][i] / matrix[i][i];for(k = i; k <= n + 1; k++)matrix[j][k] -= matrix[i][k] * tmp;}}for(i = n; i >= 1; i--){double t = matrix[i][n + 1];for(j = n; j > i; j--)t -= ans[j] * matrix[i][j];ans[i] = t / matrix[i][i];}
}

#include<iostream>
#include<cstring>
#include<string>
#include<cstdio>
#include<cstdlib>
#include<algorithm>
#include<vector>
#include<cmath>
using namespace std;const int N = 20;
double matrix[N][N], last[N], t, ans[N];
int n;inline int read(){int i = 0, f = 1; char ch = getchar();for(; (ch < '0' || ch > '9') && ch != '-'; ch = getchar());if(ch == '-') f = -1, ch = getchar();for(; ch >= '0' && ch <= '9'; ch = getchar())i = (i << 3) + (i << 1) + (ch -'0');return i * f;
}inline void wr(int x){if(x < 0) putchar('-'), x = -x;if(x > 9) wr(x / 10);putchar(x % 10 + '0');
}inline void gauss(){int i, j, l, k;for(i = 1; i <= n; i++){l = i;for(j = i + 1; j <= n; j++) if(fabs(matrix[j][i]) > fabs(matrix[l][i])) l = j;if(l != i) for(j = i; j <= n + 1; j++)swap(matrix[i][j], matrix[l][j]);for(j = i + 1; j <= n; j++){double tmp = matrix[j][i] / matrix[i][i];for(k = i; k <= n + 1; k++) matrix[j][k] -= matrix[i][k] * tmp;}}for(i = n; i >= 1; i--){double tmp = matrix[i][n + 1];for(j = n; j > i; j--)tmp -= ans[j] * matrix[i][j];ans[i] = tmp / matrix[i][i];}
}int main(){n = read();for(int i = 1; i <= n; i++) scanf("%lf", &last[i]);for(int i = 1; i <= n; i++){t = 0;for(int j = 1; j <= n; j++){double tmp; scanf("%lf", &tmp);matrix[i][j] = 2 * (tmp - last[j]);t += tmp * tmp - last[j] * last[j];last[j] = tmp;}matrix[i][n + 1] = t;}gauss();for(int i = 1; i <= n; i++){if(i < n) printf("%.3lf ", ans[i]);else printf("%.3lf\n", ans[i]);}return 0;
}

#include<iostream>
#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<string>
#include<cmath>
#include<algorithm>
#include<vector>
#define eps 1e-10
using namespace std;const int N = 600;
double matrix[N][N], ans[N], ret;
int n, m, num, degree[N];
int st[500000], ed[500000];
double gg[500000];inline void addEdge(const int &u, const int &v){degree[u]++;degree[v]++;st[++num] = u, ed[num] = v;
}inline int read(){int i = 0, f = 1; char ch = getchar();for(; (ch < '0' || ch > '9') && ch != '-'; ch = getchar());if(ch == '-') f = -1, ch = getchar();for(; ch >= '0' && ch <= '9'; ch = getchar())i = (i << 3) + (i << 1) + (ch -'0');return i * f;
}inline void gauss(){int i, j, l, k;for(i = 1; i <= n; i++){l = i;for(j = i + 1; j <= n; j++) if(fabs(matrix[j][i]) > fabs(matrix[l][i])) l = j;if(l != i) for(j = i; j <= n + 1; j++)swap(matrix[i][j], matrix[l][j]);for(j = i + 1; j <= n; j++){double tmp = matrix[j][i] / matrix[i][i];for(k = i; k <= n + 1; k++) matrix[j][k] -= matrix[i][k] * tmp;}}for(i = n; i >= 1; i--){double tmp = matrix[i][n + 1];for(j = n; j > i; j--)tmp -= ans[j] * matrix[i][j];ans[i] = tmp / matrix[i][i];}
}inline bool cmp (double a, double b){return a > b;
}int main(){n = read(), m = read();for(int i = 1; i <= m; i++){int u = read(), v = read();addEdge(u, v);}int i, j;for(i = 1; i <= m; i++){matrix[st[i]][ed[i]] += 1.0 /degree[ed[i]];matrix[ed[i]][st[i]] += 1.0 /degree[st[i]];}for(i = 1; i <= n; i++) matrix[n][i] = 0;  for(i = 1; i <= n; i++) matrix[i][i] = -1.0;matrix[1][n + 1] = -1.0;gauss();for(i = 1; i <= m; i++)gg[i] = ans[st[i]] / degree[st[i]] + ans[ed[i]] / degree[ed[i]];sort(gg + 1, gg + m + 1, cmp);for(i = 1; i <= m; i++) ret += gg[i] * i;printf("%.3f\n", ret);return 0;
}

#include<iostream>
#include<cstring>
#include<string>
#include<algorithm>
#include<cstdio>
#include<cstdlib>
#include<cmath>
using namespace std;const int N = 105, M = 10005;
int n, m;
int ecnt, st[M << 1], ed[M << 1], len[M << 1], degree[N];
double matrix[N][N], ans[N], ret;inline void addEdge(const int &u, const int &v, const int &l){st[++ecnt] = u, ed[ecnt] = v, len[ecnt] = l; degree[u]++;if(u != v) st[++ecnt] = v, ed[ecnt] = u, len[ecnt] = l, degree[v]++;
}inline void gauss(){int i, j, k, l;for(i = 1; i <= n; i++){l = i;for(j = i + 1; j <= n; j++)if(fabs(matrix[j][i]) > fabs(matrix[l][i])) l = j;if(l != i) for(j = i; j <= n + 1; j++)swap(matrix[i][j], matrix[l][j]);for(j = i + 1; j <= n; j++){double tmp = matrix[j][i] / matrix[i][i];for(k = i; k <= n + 1; k++)matrix[j][k] -= matrix[i][k] * tmp;}}for(i = n; i >= 1; i--){double t = matrix[i][n + 1];for(j = n; j > i; j--)t -= ans[j] * matrix[i][j];ans[i] = t / matrix[i][i];}
}int main(){scanf("%d%d", &n, &m);int i, j, k;for(i = 1; i <= m; i++){int u, v, w; scanf("%d%d%d", &u, &v, &w);addEdge(u, v, w);}for(i = 0; i <= 30; i++){memset(matrix, 0, sizeof matrix);memset(ans, 0, sizeof ans);for(j = 1; j <= n; j++) matrix[j][j] = 1;for(j = 1; j <= ecnt; j++){int l = len[j], u = st[j], v = ed[j];if(u == n) continue;if((l >> i) & 1){matrix[u][v] += 1.0 / degree[u];matrix[u][n + 1] += 1.0 / degree[u];}else matrix[u][v] -= 1.0 / degree[u];}gauss();ret += ans[1] * (1 << i);}printf("%.3f\n", ret);return 0;
}