Compilare: user.cpp: In function ‘void print_vector(std::vector<int>)’: user.cpp:12:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for( int i = 0; i < v.size(); i++ ) ^ user.cpp: In function ‘void backtrack(std::vector<int>, int, int)’: user.cpp:24:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if( v.size() == k ) ^ user.cpp: In function ‘int main()’: user.cpp:55:26: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf( f, "%d", &n ); ^