int main()
{
int n, m, i, tc;
char sz1[4], sz2[4];
scanf("%d", &tc);
while(tc--)
{
scanf("%d%d", &n, &m);
memset(cap, 0, sizeof(cap));
nn = m+8;
for(i = 0; i < m; i++)
{
scanf("%s%s", sz1, sz2);
cap[sz_idx(sz1)][7+i] = cap[sz_idx(sz2)][7+i] = 1;
}
for(i = 1; i <= 6; i++)
cap[0][i] = n/6;
for(i = 0; i < m; i++)
cap[7+i][7+m] = 1;
if(edmonds_karp() == m)
printf("YES\n");
else
printf("NO\n");
}
return 0;
}
int main() {
add_edge(0, 1, 3);
add_edge(0, 2, 3);
add_edge(1, 2, 2);
add_edge(1, 3, 3);
add_edge(2, 4, 2);
add_edge(3, 4, 1);
add_edge(3, 5, 2);
add_edge(4, 5, 3);
assert(edmonds_karp(6, 0, 5) == 5);
return 0;
}
