Compilare: main.cpp: In function 'void df(int)': main.cpp:11:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=0;i<a[x].size();++i) ~^~~~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:29:1: warning: this 'for' clause does not guard... [-Wmisleading-indentation] for (i=k;i>=1;--i) ^~~ main.cpp:31:5: note: ...this statement, but the latter is misleadingly indented as if it is guarded by the 'for' return 0; ^~~~~~