/**
 * Calculate retirement corpus needed.
 *
 * Calculates the lump sum amount required at retirement to sustain
 * monthly expenses over the retirement period, accounting for inflation
 * and investment returns.
 *
 * @param monthlyExpense Current monthly expense amount
 * @param inflationRate Annual inflation rate (as percentage, e.g., 3 for 3%)
 * @param yearsToRetirement Number of years until retirement
 * @param yearsAfterRetirement Number of years of retirement to sustain
 * @param returnRate Expected annual return rate (as percentage, e.g., 7 for 7%)
 * @returns Required retirement corpus amount (rounded)
 *
 * @example
 * // Calculate corpus needed: ₹50,000 monthly expense, 3% inflation, 20 years to retirement,
 * // 30 years after retirement, 7% returns
 * retirementCorpus(50000, 3, 20, 30, 7);
 * // => 13447265
 */
export declare function retirementCorpus(monthlyExpense: number, inflationRate: number, yearsToRetirement: number, yearsAfterRetirement: number, returnRate: number): number;