organic spectroscopy: n-phenethylacetamide base peak ion [closed]

This is the n-phenethylacetamide mass spectrum

His base peak ion is at 104 m/z. I have long been thinking about what its structure might be, but with a m/z ratio of 104 I can not think of anything plausible. Can you help me?

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• What ionisation method was used? – Waylander Jun 7 '18 at 12:42
• @Waylander With so much fragmentation it will have been electronic impact – Raoul Kessels Jun 7 '18 at 14:00
• Source Temperature: 200 °C, Sample Temperature: 150 °C, RESERVOIR: 75 eV – user3204810 Jun 7 '18 at 16:01
• @Waylander Done! Long time since I did MS :-| – Raoul Kessels Jun 8 '18 at 14:57

$\ce{C6H5-CH=CH2^+}$: $77+13+14=104$