a, b = map(int, input().split())
op = set()
oper = list()
for i in range(a):
oper = input().split()
for k in oper[1:]:
op.add(k)
print('YES' if len(op) == b else 'NO')
#include <iostream>
#include <set>
#include <string>
#include <list>
#include <iterator>
#include <algorithm>
using namespace std;
int main() {
set<int>s;
int t, x;
int lump;
cin >> t >> x;
for (int j = 0; j < t; ++j) {
int z;
cin >> z;
while (z--) {
cin >> lump;
s.insert(lump);
}
}
if (s.size() == x) {
cout << "YES" << endl;
}
else
{
cout << "NO" << endl;
}
return 0;
}107B - Basketball Team | 245A - System Administrator |
698A - Vacations | 1216B - Shooting |
368B - Sereja and Suffixes | 1665C - Tree Infection |
1665D - GCD Guess | 29A - Spit Problem |
1097B - Petr and a Combination Lock | 92A - Chips |
1665B - Array Cloning Technique | 1665A - GCD vs LCM |
118D - Caesar's Legions | 1598A - Computer Game |
1605A - AM Deviation | 1461A - String Generation |
1585B - Array Eversion | 1661C - Water the Trees |
1459A - Red-Blue Shuffle | 1661B - Getting Zero |
1661A - Array Balancing | 1649B - Game of Ball Passing |
572A - Arrays | 1455A - Strange Functions |
1566B - MIN-MEX Cut | 678C - Joty and Chocolate |
1352E - Special Elements | 1520E - Arranging The Sheep |
1157E - Minimum Array | 1661D - Progressions Covering |