Compilare: user.cpp: In function ‘int main()’: user.cpp:31:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<L[a].size();i++){ ^ user.cpp:48:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<L[a].size();i++){ ^ user.cpp:21:22: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(f,"%d",&n); ^ user.cpp:23:31: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(f,"%d%d",&a,&b); ^