#include<iostream>#include<cstdio>#include<string>#include<cstring>#include<algorithm>#include<vector>using namespace std;const int N = 3010;int d[N],f[N];bool v[N];int n,m,x,y,z;int a[N][N];int dfn[N];int curr;int b[N][N];int prim(){ int tot = 0; memset(d,63,sizeof(d)); memset(v,0,sizeof(v)); memset(f,0,sizeof(f)); v[0] = 1; d[0] = 0; for (int i = 1; i < n; i++) { d[i] = a[0][i]; f[i] = 0; } for (int i = 1; i < n; i++) { int k = 0,minn = 1000000000; for (int j = 0; j < n; j++) if (!v[j] && d[j] < minn) { minn = d[j]; k = j; } tot += d[k]; v[k] = 1; for (int j = 0; j < n; j++) if (!v[j] && d[j] > a[k][j]) { d[j] = a[k][j]; f[j] = k; } } return tot;}void dfs(int x){ for (int i = 0; i < n; i++) if (f[i] == x && a[x][i] < 1000000000 && a[x][i] != -1) { dfs(i); for (int j = 0; j < n; j++) b[x][j] = min(b[x][j],b[i][j]); } for (int i = 0; i < n; i++) if (i != f[x]) b[x][i] = min(b[x][i],a[x][i]);}int main(){ while (scanf("%d%d",&n,&m) != EOF) { if (n == 0 && m ==0) break; memset(a,63,sizeof(a)); for (int i = 1; i <= m; i++) { scanf("%d%d%d",&x,&y,&z); if (x != y) a[x][y] =a[y][x] = z; } int ans = prim(); memset(b,63,sizeof(b)); for (int i = 0; i < n; i++) a[i][i] = -1; f[0] = -1; dfs(0); int q; scanf("%d",&q); long long sum = 0; //cout<<ans<<endl; for (int i = 0; i < q; i++) { scanf("%d%d%d",&x,&y,&z); if (f[x] == y) { int minn = 1000000000; sum = sum + ans; sum -= a[x][y]; for (int j = 0; j < n; j++) if (j != y && b[x][j] != -1) minn = min(minn,b[x][j]); for (int j = 0; j < n; j++) if (f[j] == x && b[j][y] != -1) minn = min(minn,b[j][y]); minn = min(minn,z); sum += minn; } else if (f[y] == x) { int minn = 1000000000; sum = sum + ans; sum -= a[y][x]; for (int j = 0; j < n; j++) if (j != x && b[y][j] != -1) minn = min(minn,b[y][j]); for (int j = 0; j < n; j++) if (f[j] == y && b[j][x] != -1) minn = min(minn,b[j][x]); minn = min(minn,z); sum += minn; } else sum += ans; } double fin = sum; fin = fin / q; printf("%.4fn",fin); } return 0;}
