Compilare: user.cpp: In function ‘int main()’: user.cpp:36:48: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(;ind[j]<data[j].size()&&data[j][ind[j]]<val;ind[j]++); ^ user.cpp:37:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(data[j][ind[j]]!=val) { ^ user.cpp:47:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < sol.size(); ++i) ^