Latvian - Polerio variation
1. e4 e5 2. Nf3 f5 3. Bc4 fxe4 4. Nxe5 d5
White pushes the king's pawn to e4. Black advances the king's pawn to e5. White develops the knight to f3.
Black advances the f-pawn to f5. White develops the light-squared bishop to c4. Black captures on e4 with the f-pawn.
White captures with the knight on e5. Black pushes the queen's pawn to d5.