int main() {
// freopen("in.txt", "r+t", stdin);
// freopen("out.txt", "w+t", stdout);
int n, m, q, t;
int cases = 0;
while (scanf("%d %d", &n, &m) == 2 && n) {
tree.init();
for (int i = 1; i <= n; i++)
scanf("%d", &w[i]);
for (int i = 1; i <= m; i++)
scanf("%d %d", &edgeX[i], &edgeY[i]);
int exists[MAXM] = {};
for (int i = 1; i <= m; i++)
exists[i] = 1;
for (q = 0; scanf("%s", cmd[q]) == 1 && cmd[q][0] != 'E'; q++) {
if (cmd[q][0] == 'D')
scanf("%d", &QX[q]), exists[QX[q]] = 0;
else if (cmd[q][0] == 'C')
scanf("%d %d", &QX[q], &QY[q]), t = QY[q], QY[q] = w[QX[q]], w[QX[q]] = t;
else if (cmd[q][0] == 'Q')
scanf("%d %d", &QX[q], &QY[q]);
}
for (int i = 1; i <= n; i++)
root[i] = null;
for (int i = 1; i <= n; i++)
tree.insert(root[i], w[i]);
initDisjointSet(n);
for (int i = 1; i <= m; i++)
if (exists[i] == 1)
joint(edgeX[i], edgeY[i]);
double ret = 0, cnt = 0;
for (int i = q - 1; i >= 0; i--) {
if (cmd[i][0] == 'D')
joint(edgeX[QX[i]], edgeY[QX[i]]);
else if (cmd[i][0] == 'C')
changeVertex(QX[i], QY[i]);
else if (cmd[i][0] == 'Q') {
cnt++;
node* v = tree.rkth_element(root[findp(QX[i])], QY[i]);
if (v == null) /*puts("undefined")*/;
else ret += v->key/*, printf("kth %d\n", v->key)*/;
}
}
ret /= cnt;
printf("Case %d: %lf\n", ++cases, ret);
}
return 0;
}
JobSchedule(job jobs[])
{
int f[50],l,ji[50],m,b,q,k,i;
qsort(jobs,n,sizeof(job),jobCmp);
b = min(n,4);
initDisjointSet(b);
k = 0;
for (i = 0 ;i<= b;i++)
f[i] = i;
for (i = 0 ;i<= (n-1);i++)
{
q = CFind(min(5, jobs[i].deadline));
if (f[q] != 0)
{
ji[k++] = jobs[i].id;
m = CFind(f[q] - 1);
Wunion(m, q);
f[q] = f[m];
}
}
for(l=0;l<b;l++)
printf("%d\t",ji[l]);
}
