https://mirror.codeforces.com/problemset/problem/1933/B↵
https://mirror.codeforces.com/problemset/problem/1971/C↵
https://mirror.codeforces.com/contest/1554/problem/A↵
https://mirror.codeforces.com/problemset/problem/1883/B↵
https://mirror.codeforces.com/problemset/problem/1968/A↵
https://mirror.codeforces.com/problemset/problem/1859/A↵
https://mirror.codeforces.com/problemset/problem/1843/C↵
https://mirror.codeforces.com/problemset/problem/1881/A↵
https://mirror.codeforces.com/problemset/problem/1974/A↵
https://mirror.codeforces.com/problemset/problem/1862/B↵
https://mirror.codeforces.com/problemset/problem/1633/A
https://mirror.codeforces.com/problemset/problem/1971/C↵
https://mirror.codeforces.com/contest/1554/problem/A↵
https://mirror.codeforces.com/problemset/problem/1883/B↵
https://mirror.codeforces.com/problemset/problem/1968/A↵
https://mirror.codeforces.com/problemset/problem/1859/A↵
https://mirror.codeforces.com/problemset/problem/1843/C↵
https://mirror.codeforces.com/problemset/problem/1881/A↵
https://mirror.codeforces.com/problemset/problem/1974/A↵
https://mirror.codeforces.com/problemset/problem/1862/B↵
https://mirror.codeforces.com/problemset/problem/1633/A