Compilare: user.cpp: In function ‘int main()’: user.cpp:18:32: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(f,"%d%d%d",&n,&d,&k); ^ user.cpp:19:47: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] for (i=1;i<=d;i++) {fscanf(f,"%d%d",&x,&y); a[x][y]=1; v[i].x=x; v[i].y=y;} ^ user.cpp:20:47: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] for (i=1;i<=k;i++) {fscanf(f,"%d%d",&x,&y); a[x][y]=-1; b[x]++;} ^