Fixed invalid syntax error

main.cpp

@@ -32,7 +32,7 @@ int main(int argc, char *argv[])
 		correct_guesses.emplace_back(num);
 
 		accuracy -= abs(user_guess - num) / 100.;
-		accuracy = accuracy > 0 : -accuracy;
+		accuracy = accuracy > 0 ? accuracy : -accuracy;
 		num = gen.get_next_num();
 	}