Compilare: user.c: In function ‘main’: user.c:98:24: warning: implicit declaration of function ‘sqrt’ [-Wimplicit-function-declaration] fprintf(g,"%.8f\n",sqrt(ans)); ^ user.c:98:24: warning: incompatible implicit declaration of built-in function ‘sqrt’ user.c:98:24: note: include ‘<math.h>’ or provide a declaration of ‘sqrt’ user.c:87:5: warning: ignoring return value of ‘fscanf’, declared with attribute warn_unused_result [-Wunused-result] fscanf(f,"%d",&n); ^ user.c:89:9: warning: ignoring return value of ‘fscanf’, declared with attribute warn_unused_result [-Wunused-result] fscanf(f,"%d%d",&a[i].x, &a[i].y); ^