awk '{print gensub(/([0-9])\+/,"\\1x","G",$0)}' | awk '{print gensub(/([0-9])\-/,"\\1+","G",$0)}' | awk '{print gensub(/([0-9])x/,"\\1-","G",$0)}' | python -c "import sys;print(eval(sys.argv[1]))"