cf
/
mirror
Problemset
Contests
Favorites
Profile
Tools
Settings
Problemset
Contests
Favorites
Profile
Complexity
Stress
Graph
Templates
Crawler
Fixed Point Guessing
☆
save
CF
1698D
1600
· expert
1s
256 MB
⇄ interactive
#binary search
#constructive algorithms
#interactive
hide
Examples
Sample 1
of 1
Input
copy
2
5
1 2 4 5
1 3 5
3
1
Output
copy
? 1 4
? 3 5
! 2
? 1 1
! 1
58%
1698D.cpp
GNU C++20 (64)
GNU C11
Python 3
PyPy 3
Java 21
Rust
Go
C#
JavaScript
Ruby
Pascal
Haskell
Kotlin · no run
loading editor…
Ln
11
·
137 B
GNU C++20 (64)
⟲ Reset
Run samples
Submit
▸
Custom test
run your code against any stdin
▸
Stress test
run a brute + generator against your solution to find a failing case
▸
Editorial & videos
official tutorial + youtube — hidden while contest is live