Thirteen years, in the case of Muhammad Idrees.
In 1999, Mr Idrees left his wife and four young sons in Pakistan's port city of Karachi to attend to his sick father in the Indian city of Kanpur. He was born in India, and had moved to Pakistan and become its citizen after he married a cousin in Karachi.
His father died soon after he reached Kanpur. In the chaos and grief that followed this personal loss, Mr Idrees overstayed for three days and his visa ran out.
So did his luck.
When he went to the authorities in Kanpur to seek a visa extension, they suspected him of spying for Pakistan and put him behind the bars. It took 10 years for a court to exonerate him of the charge, fine him 500 rupees ($9.17; £5.68) for overstaying and order his repatriation.
Justice delayed is justice denied, and in the case of Mr Idrees, even justice delivered did not turn out to be liberating.
For 13 years in all, he has been trying to return home without success.
According to India's Ministry of External Affairs, Mr Idrees travelled to India on a Pakistani passport (number G057703), issued in Karachi, on 10 May 1999. To add to his woes, his passport expired in 2003.
But Pakistan denies he is a citizen, and believes he has separated from his wife and has been disowned by his family.
"Our interior ministry told us that he's not a Pakistani citizen. To our knowledge he's separated from his wife and his in-laws. They disown him. We have communicated this to Indian authorities," Manzoor Ali Memon, spokesperson of Pakistan's High Commission in India, told me.
Today, at 40, Muhammad Idrees is a nowhere man, a victim of unkind fate and hostile borders.
I met him in Kanpur, a fume-choked industrial city in Uttar Pradesh, on a balmy morning recently to listen to his heart-rending story.
Mr Idrees is a frail man with a gaunt face and intense eyes. He's dressed in white shirt and trousers and his only possession, a cloth bag, is slung around his neck. It contains some fraying papers, a comb, a tooth brush, a tube of tooth paste, a towel and some fading family pictures.
We walk to the relative solitude of the banks of the Ganges and sit down. Mr Idrees catches his breath, looks into the distance and begins talking in a clear, low voice.
He says he spends his waking hours clinging onto memories of time spent with his family back home in Karachi, where he ran a small business selling leather goods. It feels like an eternity, he says.
"I would take my wife and our four children on my motorbike for a drive down the windswept seaside in Karachi. We would laugh and chat. We would stop to have ice creams. Just like any other family."
This was before his world turned black.
It was before, he says, two nations and their strange, intractable ways, conspired to deny him from returning home.
"India should have sorted out my case in time and not wasted my precious years. Pakistan should have given me a fresh passport. I wasted 10 years in a court and three years chasing officials. Why are they ruining my life?"
He tells me stories of his life spent as a castaway, denied his citizenship and stripped of his livelihood and dignity.
They are stories of a time when he began making small leather bags after being bailed out of prison to pay for his legal fees. Of a time when his parents died and his relatives, including his brothers, in Kanpur, broke off all contact and denied him a room in his father's home. Of a time when he moved into a shelter home where, he says, he "began to lose it" after having an accident.
"I felt like taking my life. I behaved like a mad man. But I received no treatment. Instead, they kicked me out of the home," he says calmly.
Since then he has wandered the streets alone, begging and living off the charity of kind-hearted citizens. At night, he has has slept in government hospitals, abandoned buildings, empty offices - cold, impersonal public buildings that are the last refuge of a hopeless vagrant.
"It's been a painful journey. If I have lived through such hellish experiences, it's all because I want to return home and meet my children," says Mr Idrees.
"Just give me back my life."
To find out why nobody's listening to him, I spent three days with him trying to meet officials and find out why his countless trips to them had yielded no results.
Eventually, I manage to meet Manoj Aggarwal, the senior-most official of Kanpur city, in his office.
"It's not an easy case. We are in touch with the Pakistani embassy [to issue Mr Idrees a passport]," he tells me.
But how can there be no solution in sight after 13 years?
"We are waiting for a response from Pakistan. But it's Idrees's fault as well. He shouldn't have overstayed," says Mr Aggarwal.
Until he is repatriated, I ask, should the state not be taking care of Mr Idrees, giving him food, shelter and work?
"He was given shelter," says Mr Aggarwal. "But he keeps running away."
But hasn't Mr Idrees been thrown out of a shelter home, which refuses to take him back?
"He has been helped by charity."
What about ensuring him a permanent shelter at least until he is returned home? I ask.
"Yes," says Mr Agarwal bluntly.
What happens if Pakistan refuses to issue him a fresh passport?
"Let's see."
The conversation ends, and we leave his office. We return to the banks of Ganges.
"I love to come here and spend the day. Nobody bothers you. I have felt suicidal so many times, but when I sit here the water calms me down," he says.
He takes out the family pictures, his wedding card, his nationality papers from his bag.
"See, these are my four children and this is my wife," he says, showing me a picture of what looks like a glowing, contented family.  A wide smile runs across his face.
"I know my wife is angry with me. I know she remembers our fights. But then all couples fight, don't they? Once I am back everything will be fine.
"My sons must have grown up so much. I will have to treat them as grown-ups when we meet again," he says.
I keep quiet and manage a faint smile.
I don't have the heart to tell him that we got in touch with Shabana, his wife, in Karachi.
"Idrees does not exist for us any more," she told our reporter.
She did not elaborate.
Mr Idrees has promised to call me and give me the good news when he gets to return home. I am still waiting.
"Life is short," he told me before we parted. "I don't think I have many years left. I  just want to spend my time left with my children, my wife.
"It is not asking for too much, is it?"
What price can a man end up paying up for the crime of overstaying in a foreign land for three days?