function L=lifepowr(T)
% input vector T of length 8, lifetimes of components of montreal 
% power grid. Outputs lifetime L of the system.
L1=min(T([1 2 7]));
L2=min(T([1 5 6 8]));
L3=min(T([1 2 3 4 8]));
L4=min(T([1 3 4 5 6 7]));
L=max([L1,L2,L3,L4]);