Compilare: main.cpp: In function 'bool cmp(int, int)': main.cpp:15:15: warning: statement has no effect [-Wunused-value] comuni[a] > comuni[b]; ~~~~~~~~~~^~~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:35:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j = 0; j < v[i].size(); j ++) { ~~^~~~~~~~~~~~~ main.cpp: In function 'bool cmp(int, int)': main.cpp:16:1: warning: control reaches end of non-void function [-Wreturn-type] } ^