def sumn(n): return n*(n+1)/2
x1,y1,x2,y2,d=map(int,raw_input().split())
if x1>=0: xx=[[x1,x2]]
elif x2<=0:xx=[[-x2,-x1]]
else:xx=[[1,-x1],[0,x2]]
if y1>=0: yy=[[y1,y2]]
elif y2<=0:yy=[[-y2,-y1]]
else:yy=[[1,-y1],[0,y2]]
ans=0
for x in xx:
    for y in yy:
        if x[0]+y[0]>d:continue
        if x[1]+y[1]<=d:
            ans+=(x[1]-x[0]+1)*(y[1]-y[0]+1)
            continue
        if x[1]+y[0] >= d:
            if x[0]+y[1]>=d:
                tx=d-y[0]
                ans+=sumn(tx-x[0]+1)
            else:
                tx=d-y[1]
                e=y[1]-y[0]+1
                ans+=sumn(e)+e*(tx-x[0])
        else:
            if x[0]+y[1]>=d:
                ty=d-x[1]
                e=x[1]-x[0]+1
                ans+=sumn(e)+e*(ty-y[0])
            else:
                tx=d-y[1]
                ans+=(x[1]-x[0]+1)*(y[1]-y[0]+1)-sumn(x[1]-tx)
print ans