Compilare: user.cpp: In function ‘int main()’: user.cpp:18:25: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(IN,"%d%d",&N,&M); ^ user.cpp:25:26: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(IN,"%d%d",&X,&Y); ^ user.cpp:51:17: warning: ‘start’ may be used uninitialized in this function [-Wmaybe-uninitialized] start=f[start]; ^