Task: Identify the primary emotion conveyed in the tweet and assign it to either 'neutral or no emotion' or one or more of the provided emotions (anger, anticipation, disgust, fear, joy, love, optimism, pessimism, sadness, surprise, trust) that best capture the tweeter's mental state.
Tweet: Africa has unique and tremendous problems with war, overpopulation, starvation and tribalism which makes moving Africa forward hard.
This tweet contains emotions: 
disgust, sadness