Compilare: main.cpp: In function 'int main()': main.cpp:33:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<v[nr].size(); ++i) ~^~~~~~~~~~~~~ main.cpp:15:31: warning: ignoring return value of 'int fscanf(FILE*, const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] fscanf(in, "%d%d", &n, &m); ^ main.cpp:20:35: warning: ignoring return value of 'int fscanf(FILE*, const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] fscanf(in, "%d%d", &x, &y); ^