Compilare: user.c: In function ‘main’: user.c:20:40: warning: unused variable ‘b’ [-Wunused-variable] int q,n,m,i,j,nr,xtan,ytan,x,y,a,r,b; ^ user.c:20:36: warning: unused variable ‘a’ [-Wunused-variable] int q,n,m,i,j,nr,xtan,ytan,x,y,a,r,b; ^ user.c:21:12: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] freopen("ace.in","r",stdin); ^ user.c:22:12: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] freopen("ace.out","w",stdout); ^