A Retail chain has seven branches in a city namely R1, R2, R3, R4, R5, R6, R7 and a central distribution center (DC). The nearest branch to the DC is R6 which is in the south of DC and is 9 Km away from DC. R2 is 17 Km away from DC in the west. The branch R1 is 11 Km away R2 further in the west. The branch R3 is 11 Km in the north east of R1. R4 is 13 Km from R3 in the east. R5 is 11 Km in the north east of the distribution center. In the north east of R6 is R7 and distance between them is 15 Km. The distance between R1 and R6, R2 and R6, R6 and R5 is 23 Km, 19 Km, 13 Km respectively. R3 is 14 Km away from the DC in the north west direction, while R2 is also 14 Km away from R4 in the north east direction of R2. A truck carrying some goods starts from the distribution center and has to cover at least four stores in a single trip. There is an essential good that has to be delivered in the store R7, but the delivery at R7 has to be done in the end, so what is the shortest distance the truck would travel?