Compilare: main.cpp: In function 'bool make_relations()': main.cpp:36:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<alb[only[pos]].size();i++) ~^~~~~~~~~~~~~~~~~~~~~~ main.cpp:43:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j=0;j<alb[who].size();j++) ~^~~~~~~~~~~~~~~~ main.cpp:74:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<negru[only[pos]].size();i++) ~^~~~~~~~~~~~~~~~~~~~~~~~ main.cpp:81:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j=0;j<negru[who].size();j++) ~^~~~~~~~~~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:143:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(ans.size()!=2*n) ~~~~~~~~~~^~~~~ main.cpp:148:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<ans.size();i++) ~^~~~~~~~~~~ main.cpp: In function 'bool make_relations()': main.cpp:91:1: warning: control reaches end of non-void function [-Wreturn-type] } ^