Compilare: user.cpp: In function ‘int main()’: user.cpp:42:21: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(fin,"%d",&n); ^ user.cpp:44:53: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] for(i=1;i<=n;++i)fscanf(fin,"%d%d",&v[i].x,&v[i].y); ^ user.cpp: In function ‘void prim()’: user.cpp:35:17: warning: ‘y’ may be used uninitialized in this function [-Wmaybe-uninitialized] s[x]=1;s[y]=1;S+=minn; ^ user.cpp:35:10: warning: ‘x’ may be used uninitialized in this function [-Wmaybe-uninitialized] s[x]=1;s[y]=1;S+=minn; ^