Police are looking for two men in their 20s who robbed three people in separate incidents on the F train over the past couple months.

In the first incident, the men grabbed a 23-year-old man from behind as he walked up the stairs of the 169th Street F station on Sept 2. They threw him to the ground and punched him before taking his wallet from his back pocket just after 4 a.m.

About a month later, the suspects attacked a 30-year-old man who was riding the F train at about 9 a.m., police said. One of the suspects punched the man in the face and demanded his iPad on Sept. 30.

But the victim refused and although the suspects followed him off the train at the Sutphin Boulevard stop, they fled empty-handed, police said.

On Oct. 8 they struck again, grabbing a cellphone from a 33-year-old man's hands as he sat on the F train at about 1:40 p.m., police said. The men jumped off the train at the Parsons Boulevard stop and the victim tried to chase them.

One of the suspects punched the man in his face before running away, police said.