Compilare: main.cpp: In function 'int main()': main.cpp:55:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<v.size()-1; i++) ~^~~~~~~~~~~ main.cpp:61:37: warning: format '%d' expects argument of type 'int', but argument 3 has type 'std::vector<std::pair<int, int> >::size_type {aka long unsigned int}' [-Wformat=] fprintf(fout, "%d\n", ans.size()); ^ main.cpp:19:26: warning: ignoring return value of 'int fscanf(FILE*, const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] fscanf(fin, "%d", &n); ^ main.cpp:21:36: warning: ignoring return value of 'int fscanf(FILE*, const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] fscanf(fin, "%d", &next[i]); ^