local n=io.read("n")
local t={}
for i=1,n do
    local x,l=io.read("n","n")
    t[i]={x+l,x-l}
end
table.sort(t,function(x,y)
    return x[1]<y[1]
end)

local counter,eoa=0,-(10^9+1)
for i=1,n do
    if eoa<=t[i][2] then
        counter=counter+1
        eoa=t[i][1]
    end
end
print(counter)