Compilare: user.cpp: In function ‘int main()’: user.cpp:40:25: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<a[n].size();++i) ^ user.cpp:45:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(j=0;j<a[i].size();++j) ^ user.cpp:53:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(j=0;j<a[i].size();++j) ^ user.cpp: In function ‘void ciur()’: user.cpp:20:9: warning: iteration 199u invokes undefined behavior [-Waggressive-loop-optimizations] if(a1[i]==0) ^ user.cpp:19:1: note: containing loop for(i=3;i<=4001;i=i+2) ^