Compilare: user.cpp:6:23: warning: suggest parentheses around ‘+’ inside ‘<<’ [-Wparentheses] unsigned int n,l,u,v[1<<20+1]; ^ user.cpp: In function ‘long long int solve(int)’: user.cpp:12:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=1;i<=n;++i) ^ user.cpp:15:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(usu.size()>k) ^ user.cpp: In function ‘int main()’: user.cpp:28:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=1;i<=n;++i) f>>v[i]; ^