MILAN, Feb 5 (Reuters) - Italy’s biggest bank Intesa Sanpaolo posted a 3.3 billion euro ($4 billion) profit for 2020 after a similar-size loss in the fourth quarter when it used an accounting boost from its takeover of rival UBI to fund restructuring and clean-up costs. Intesa Sanpaolo last year snatched the healthiest among Italy’s second-tier banks following a strenuous takeover battle, reaping a multi-billion paper profit thanks to discounted market valuations for banks. ($1 = 0.8348 euros) (Reporting by Valentina Za; editing by Agnieszka Flak)