Compilare: main.cpp: In function 'int pairup(int)': main.cpp:14:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<v[x].size();i++) ~^~~~~~~~~~~~ main.cpp: In function 'void dfs(int)': main.cpp:29:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<v[x].size();i++) ~^~~~~~~~~~~~ main.cpp: In function 'int pairup(int)': main.cpp:25:1: warning: control reaches end of non-void function [-Wreturn-type] } ^