Task: Identify new Google Sheets rows

n8n workflow JSON:
{"nodes":[{"name":"On clicking 'execute'","type":"n8n-nodes-base.manualTrigger","position":[240,300],"parameters":{},"typeVersion":1},{"name":"Is new?","type":"n8n-nodes-base.if","position":[680,300],"parameters":{"conditions":{"string":[{"value1":"={{$json[\"Processed\"]}}","operation":"isEmpty"}]}},"typeVersion":1},{"name":"Do something here","type":"n8n-nodes-base.noOp","position":[900,100],"parameters":{},"typeVersion":1},{"name":"Mark Row as processed","type":"n8n-nodes-base.googleSheets","position":[1120,300],"parameters":{"key":"ID","options":{},"sheetId":"1SdnwaIJ6xwaZl006FmK2j4f-b00tq7tT7iQgdfe7Qh4","operation":"update","authentication":"oAuth2"},"credentials":{"googleSheetsOAuth2Api":{"id":"228","name":"Google Sheets account"}},"typeVersion":1},{"name":"Read sheet","type":"n8n-nodes-base.googleSheets","position":[460,300],"parameters":{"options":{},"sheetId":"1SdnwaIJ6xwaZl006FmK2j4f-b00tq7tT7iQgdfe7Qh4","authentication":"oAuth2"},"credentials":{"googleSheetsOAuth2Api":{"id":"228","name":"Google Sheets account"}},"typeVersion":1},{"name":"Set processed value","type":"n8n-nodes-base.set","position":[900,300],"parameters":{"values":{"string":[{"name":"Processed","value":"={{ $now.toISO() }}"}]},"options":{}},"typeVersion":1},{"name":"Run every 5 minutes","type":"n8n-nodes-base.interval","position":[240,100],"parameters":{"unit":"minutes","interval":5},"typeVersion":1}],"connections":{"Is new?":{"main":[[{"node":"Do something here","type":"main","index":0},{"node":"Set processed value","type":"main","index":0}]]},"Read sheet":{"main":[[{"node":"Is new?","type":"main","index":0}]]},"Run every 5 minutes":{"main":[[{"node":"Read sheet","type":"main","index":0}]]},"Set processed value":{"main":[[{"node":"Mark Row as processed","type":"main","index":0}]]},"On clicking 'execute'":{"main":[[{"node":"Read sheet","type":"main","index":0}]]}}}