tabletennis.cpp: In function 'int main()':
tabletennis.cpp:49:16: warning: comparison of integer expressions of different signedness: 'std::vector<int>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
49 | if(ans.size()==n-k)break;
| ~~~~~~~~~~^~~~~
tabletennis.cpp:13:4: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
13 | sf("%d%d",&n,&k);
| ^
tabletennis.cpp:16:5: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
16 | sf("%d",&v);
| ^
tabletennis.cpp:20:14: warning: 'r' may be used uninitialized in this function [-Wmaybe-uninitialized]
20 | int res=0,l,r;
| ^
tabletennis.cpp:39:12: warning: 'l' may be used uninitialized in this function [-Wmaybe-uninitialized]
39 | ans.pb(s[l]);ans.pb(s[r]);
| ^