Solve the following sql problem:
How many streets with restaurants are there in the Northern California region?

Schema:
SCHEMA:
- Table: geographic
  - Column: city
    - Samples: [alameda, alamo, albany, alviso, american canyon]
  - Column: county
    - Samples: [alameda county, contra costa county, alameda county, santa clara county, unknown]
  - Column: region
    - Samples: [bay area, bay area, bay area, bay area, bay area]
- Table: generalinfo
  - Column: id_restaurant
    - Samples: [1, 2, 3, 4, 5]
  - Column: label
    - Samples: [sparky's diner, kabul afghan cuisine, helmand restaurant, afghani house, kabul afghan cusine]
  - Column: food_type
    - Samples: [24 hour diner, afghani, afghani, afghani, afghani]
  - Column: city
    - Samples: [san francisco, san carlos, san francisco, sunnyvale, sunnyvale]
  - Column: review
    - Samples: [2.3, 3.8, 4.0, 3.6, 3.7]
- Table: location
  - Column: id_restaurant
    - Samples: [1, 2, 3, 4, 5]
  - Column: street_num
    - Samples: [242, 135, 430, 1103, 833]
  - Column: street_name
    - Samples: [church st, el camino real, broadway, e. el camino real, w. el camino real]
  - Column: city
    - Samples: [san francisco, san carlos, san francisco, sunnyvale, sunnyvale]

SELECT COUNT(T1.city) FROM geographic AS T1 INNER JOIN location AS T2 ON T1.city = T2.city WHERE T1.region = 'northern california'