x = STDIN.lines.map{|l|l.split.map{|l|l.to_i}}
a= x[1][0] - x[0][0]
b= x[1][0] - x[0][0]
c= x[1][0] - x[0][0]
d= x[1][0] - x[0][0]
e= x[1][0] - x[0][0]
f= x[1][0] - x[0][0]
g= x[1][0] - x[0][0]
h= x[1][0] - x[0][0]
i= x[1][0] - x[0][0]
print a