When itogon, benguet is the city/municipality and 1st class is the income classification how many measurements of population in 2010?
CREATE TABLE "table1_29289372_1" (
  "city_municipality" text,
  "population_2010" real,
  "area_km" text,
  "pop_density_per_km" text,
  "income_classification" text
);
SELECT COUNT("population_2010") FROM "table1_29289372_1" WHERE "income_classification"='1st Class' AND "city_municipality"='Itogon, Benguet';