Compilare: main.cpp: In function 'int main()': main.cpp:21:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<v[x].size();i++) ~^~~~~~~~~~~~ main.cpp:31:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<v[x].size();i++) ~^~~~~~~~~~~~ main.cpp:30:8: warning: unused variable 'ok' [-Wunused-variable] int ok=0; ^~ main.cpp:37:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<v[x].size();i++) ~^~~~~~~~~~~~