Act as an Operations Research Scientist. Design a mathematical model for a Multi-Echelon Inventory Optimization (MEIO) problem for a global retail company. The model should account for stochastic demand at the retail level, lead time variability at the distribution centers, and transportation costs between factories, warehouses, and stores. Formulate the objective function to minimize total holding costs and stockout costs while maintaining a service level of 95%. Explain how you would use dynamic programming or genetic algorithms to solve this NP-hard problem.