k=int(raw_input())
node=[]
prob=[]
for i in range(k):
    n,p=map(int,raw_input().split(" "))
    node.append(n)
    prob.append(p)

app=[]
app.append(1)
app.append(node[0])
temp=node[0]
flag=0
cyc=1
for i in range(k):
    temp=node[(temp-1)]
    for j in range(len(app)):
      if app[j]==temp:
          flag=1
          tem1=j;
    if flag!=1:
        app.append(temp)
    else:
        for cc in range(tem1,len(app)):
            cyc=cyc*((prob[app[cc]-1])/float(100))
        break
  
print cyc