How do you pass level 1 on sniper assassin 5

There are 4 people to shoot 3 on left and 1 on the right. 3 out of 4 are in buildings. The building to the far left building. Then another building right next to the previous building there is one on the roof. Then to the far right in the last building.

Hope this helps if not there is a video 2nd rectangle down if you failed watch that but only the 1st minute not the ten minutes.