## [Javascript (Babel Node)][1], 179 bytes ##

    process.stdin.on('data',d=>{s=0;Array.from(d+'').map(c=>{s+=/[AV]/.test(c)?1:(/[NZ]/.test(c)?2:(/[MW]/.test(c)?3:(/[CU]/.test(c)?-1:(c=='S'?-2:(c=='O'?-3:0)))))});console.log(s)})

[Try it online!][2]

This is my first code golfing. I hope I'm doing it right.

I'll be glad to get some js golfing tips (before exploring new golfing languages) and overall golfing tips.


  [1]: https://developer.mozilla.org/en-US/docs/Web/JavaScript
  [2]: https://tio.run/##TcvBisIwGATgx0lKt6mrNyUrJXgItPnFWIWVPcQkKy61KUlYEPHZa4uXzmn4hvlT/ypof@1idlZn22StM7bvO@@0DYGEaK4tcS1GRkWFPgz9egQ6WxXeqzv59e6GTYpQQm6qw3ocU5qfisNPTqINEetk/bnE@Ul8T2Q@SnWcyGIUVk8kG26aUiTROpu/Kwx1sZwlY57JSrs2uMaSxl1wGKDvt2JTVyCgLve7ouJsB5LBljPJS87gACUrBDAQHCSXLw