Compilare: main.cpp: In function 'int main()': main.cpp:36:38: warning: format '%d' expects argument of type 'int', but argument 3 has type 'std::multiset<std::pair<int, int> >::size_type {aka long unsigned int}' [-Wformat=] fprintf(fout, "%d\n",v.size()); ^ main.cpp:15:23: warning: ignoring return value of 'int fscanf(FILE*, const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] fscanf(fin, "%d",&n); ^ main.cpp:17:30: warning: ignoring return value of 'int fscanf(FILE*, const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] fscanf(fin, "%d%d",&x,&y); ^