def whatFlavors(cost, money):
    mapping = {}
    
    for i in range(len(cost)):
        current_price = cost[i]
        if current_price in mapping.keys():
            if mapping[current_price] < i + 1:
                # Print complement price index first
                print("{} {}".format(mapping[current_price], i + 1))
            else:
                print("{} {}".format(i + 1, mapping[cost[i]]))
        # Map current price index to complement price
        mapping[money - current_price] = i + 1