Compilare: user.cpp: In function ‘void backtrack(std::vector<int>, int, int)’: user.cpp:25:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if( v.size() == k ) ^ user.cpp: In function ‘int main()’: user.cpp:56:26: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf( f, "%d", &n ); ^