Is it healthy to only eat sandwich at work?

Im on night shift and I used to bring fried chicken and rice or fried pork and rice or hunts pork and beans at work but now Im struggling with money I only bring 3 layers of bread with mayonnaise in between of it. I can't afford to buy food anymore. What I do is I eat my breakfast at 3:30 pm and before work and at around 12pm is eat my sandwich at work. My job is 6-6 night duty
Is it healthy to only eat sandwich at work?
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