CONGO. The stamp is a portrait of the first president of the Republic of the Congo, Fulbert Youlou. He's also second prime minister of the Republic of the Congo. I tried to get more info about when the stamp was issued but I was unlucky :(
GUINEA. These fishes are part of the tropical fish 6 stamp set. Siganus trispilos is commonly known as the threeblotched rabbitfish and the Naso lituratus as ornagespine unicornfish. I bet these fishes would complain if they asked to write their names, being in the kindergarten!
MADAGASCAR. Here's a picture of a native from Madagascar with a spear.The stamp was issued in 1946.
Another fun learning experience for me, I hope it was fun for you to travel and learn via stamps, too!
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