Urho Kekkonen have 1st place in length of president for 3 whole terms serving (the 3rd exceptionally 10 years) * resigned during the 4th term due to poor health.
[['Urho Kekkonen', 'NOTES', '3 whole terms serving (the 3rd exceptionally 10 years) * resigned during the 4th term due to poor health'], ['Urho Kekkonen', 'RANK_BY_LENGTH_OF_TERM(S)', '1']]