Aw,Ab=map(int,raw_input().split())
Bw,Bb=map(int,raw_input().split())
C,D=map(int,raw_input().split())

if C>Ab:
    Bw+=C-Ab
    Bb+=Ab
    Aw-=C-Ab
    Ab-=Ab
else:
    Bb+=C
    Ab-=C

print Aw+min(D,Bw)