Compilare: main.cpp: In function 'int main()': main.cpp:70:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j=0;j<a[i].size();++j) ~^~~~~~~~~~~~ main.cpp:47:28: warning: ignoring return value of 'int fscanf(FILE*, const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] fscanf(f,"%d %d",&n,&m); ^ main.cpp:51:32: warning: ignoring return value of 'int fscanf(FILE*, const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] fscanf(f,"%d %d",&x,&y); ^