困難, こんなん
NA-adjective
1. difficulty, hardship, trouble, distress
euphemistic
2. infeasibility, inability (to carry out)
彼の言ってる事を理解するのは困難だ。
に
Particle
1. at (place, time), in, on, during
2. to (direction, state), toward, into
3. for (purpose)
4. because of (reason), for, with
5. by, from