Language: C

double x[100],y[100],t,u,a,b,s;n,i,j,k,c,z;main(m){for(;m=scanf("%d",&n),z=i=n;printf("%d\n",m)){for(;!z?j=--i:scanf("%lf,%lf",x+z,y+--z))for(;!z&&j--;)for(u=acos(hypot(a=x[j]-x[i],b=y[j]-y[i])/2),s=1,t=atan2(b,a);c=0,u<9&&s+3;s-=2)for(a=x[i]+cos(b=t+s*u),b=y[i]+sin(b),k=n;k--;)hypot(a-x[k],b-y[k])<1.1&&++c>m?m=c:0;}

Compiler output:
main.c:1:32: warning: data definition has no type or storage class
    1 | double x[100],y[100],t,u,a,b,s;n,i,j,k,c,z;main(m){for(;m=scanf("%d",&n),z=i=n;printf("%d\n",m)){for(;!z?j=--i:scanf("%lf,%lf",x+z,y+--z))for(;!z&&j--;)for(u=acos(hypot(a=x[j]-x[i],b=y[j]-y[i])/2),s=1,t=atan2(b,a);c=0,u<9&&s+3;s-=2)for(a=x[i]+cos(b=t+s*u),b=y[i]+sin(b),k=n;k--;)hypot(a-x[k],b-y[k])<1.1&&++c>m?m=c:0;}
      |                                ^
main.c:1:32: error: type defaults to 'int' in declaration of 'n' [-Wimplicit-int]
main.c:1:34: error: type defaults to 'int' in declaration of 'i' [-Wimplicit-int]
    1 | double x[100],y[100],t,u,a,b,s;n,i,j,k,c,z;main(m){for(;m=scanf("%d",&n),z=i=n;printf("%d\n",m)){for(;!z?j=--i:scanf("%lf,%lf",x+z,y+--z))for(;!z&&j--;)for(u=acos(hypot(a=x[j]-x[i],b=y[j]-y[i])/2),s=1,t=atan2(b,a);c=0,u<9&&s+3;s-=2)for(a=x[i]+cos(b=t+s*u),b=y[i]+sin(b),k=n;k--;)hypot(a-x[k],b-y[k])<1.1&&++c>m?m=c:0;}
      |                                  ^
main.c:1:36: error: type defaults to 'int' in declaration of 'j' [-Wimplicit-int]
    1 | double x[100],y[100],t,u,a,b,s;n,i,j,k,c,z;main(m){for(;m=scanf("%d",&n),z=i=n;printf("%d\n",m)){for(;!z?j=--i:scanf("%lf,%lf",x+z,y+--z))for(;!z&&j--;)for(u=acos(hypot(a=x[j]-x[i],b=y[j]-y[i])/2),s=1,t=atan2(b,a);c=0,u<9&&s+3;s-=2)for(a=x[i]+cos(b=t+s*u),b=y[i]+sin(b),k=n;k--;)hypot(a-x[k],b-y[k])<1.1&&++c>m?m=c:0;}
      |                                    ^
main.c:1:38: error: type defaults to 'int' in declaration of 'k' [-Wimplicit-int]
    1 | double x[100],y[100],t,u,a,b,s;n,i,j,k,c,z;main(m){for(;m=scanf("%d",&n),z=i=n;printf("%d\n",m)){for(;!z?j=--i:scanf("%lf,%lf",x+z,y+--z))for(;!z&&j--;)for(u=acos(hypot(a=x[j]-x[i],b=y[j]-y[i])/2),s=1,t=atan2(b,a);c=0,u<9&&s+3;s-=2)for(a=x[i]+cos(b=t+s*u),b=y[i]+sin(b),k=n;k--;)hypot(a-x[k],b-y[k])<1.1&&++c>m?m=c:0;}
      |                                      ^
main.c:1:40: error: type defaults to 'int' in declaration of 'c' [-Wimplicit-int]
    1 | double x[100],y[100],t,u,a,b,s;n,i,j,k,c,z;main(m){for(;m=scanf("%d",&n),z=i=n;printf("%d\n",m)){for(;!z?j=--i:scanf("%lf,%lf",x+z,y+--z))for(;!z&&j--;)for(u=acos(hypot(a=x[j]-x[i],b=y[j]-y[i])/2),s=1,t=atan2(b,a);c=0,u<9&&s+3;s-=2)for(a=x[i]+cos(b=t+s*u),b=y[i]+sin(b),k=n;k--;)hypot(a-x[k],b-y[k])<1.1&&++c>m?m=c:0;}
      |                                        ^
main.c:1:42: error: type defaults to 'int' in declaration of 'z' [-Wimplicit-int]
    1 | double x[100],y[100],t,u,a,b,s;n,i,j,k,c,z;main(m){for(;m=scanf("%d",&n),z=i=n;printf("%d\n",m)){for(;!z?j=--i:scanf("%lf,%lf",x+z,y+--z))for(;!z&&j--;)for(u=acos(hypot(a=x[j]-x[i],b=y[j]-y[i])/2),s=1,t=atan2(b,a);c=0,u<9&&s+3;s-=2)for(a=x[i]+cos(b=t+s*u),b=y[i]+sin(b),k=n;k--;)hypot(a-x[k],b-y[k])<1.1&&++c>m?m=c:0;}
      |                                          ^
main.c:1:44: error: return type defaults to 'int' [-Wimplicit-int]
    1 | double x[100],y[100],t,u,a,b,s;n,i,j,k,c,z;main(m){for(;m=scanf("%d",&n),z=i=n;printf("%d\n",m)){for(;!z?j=--i:scanf("%lf,%lf",x+z,y+--z))for(;!z&&j--;)for(u=acos(hypot(a=x[j]-x[i],b=y[j]-y[i])/2),s=1,t=atan2(b,a);c=0,u<9&&s+3;s-=2)for(a=x[i]+cos(b=t+s*u),b=y[i]+sin(b),k=n;k--;)hypot(a-x[k],b-y[k])<1.1&&++c>m?m=c:0;}
      |                                            ^~~~
main.c: In function 'main':
main.c:1:44: error: type of 'm' defaults to 'int' [-Wimplicit-int]
main.c:1:59: error: implicit declaration of function 'scanf' [-Wimplicit-function-declaration]
    1 | double x[100],y[100],t,u,a,b,s;n,i,j,k,c,z;main(m){for(;m=scanf("%d",&n),z=i=n;printf("%d\n",m)){for(;!z?j=--i:scanf("%lf,%lf",x+z,y+--z))for(;!z&&j--;)for(u=acos(hypot(a=x[j]-x[i],b=y[j]-y[i])/2),s=1,t=atan2(b,a);c=0,u<9&&s+3;s-=2)for(a=x[i]+cos(b=t+s*u),b=y[i]+sin(b),k=n;k--;)hypot(a-x[k],b-y[k])<1.1&&++c>m?m=c:0;}
      |                                                           ^~~~~
main.c:1:1: note: include '<stdio.h>' or provide a declaration of 'scanf'
  +++ |+#include <stdio.h>
    1 | double x[100],y[100],t,u,a,b,s;n,i,j,k,c,z;main(m){for(;m=scanf("%d",&n),z=i=n;printf("%d\n",m)){for(;!z?j=--i:scanf("%lf,%lf",x+z,y+--z))for(;!z&&j--;)for(u=acos(hypot(a=x[j]-x[i],b=y[j]-y[i])/2),s=1,t=atan2(b,a);c=0,u<9&&s+3;s-=2)for(a=x[i]+cos(b=t+s*u),b=y[i]+sin(b),k=n;k--;)hypot(a-x[k],b-y[k])<1.1&&++c>m?m=c:0;}
main.c:1:59: warning: incompatible implicit declaration of built-in function 'scanf' [-Wbuiltin-declaration-mismatch]
    1 | double x[100],y[100],t,u,a,b,s;n,i,j,k,c,z;main(m){for(;m=scanf("%d",&n),z=i=n;printf("%d\n",m)){for(;!z?j=--i:scanf("%lf,%lf",x+z,y+--z))for(;!z&&j--;)for(u=acos(hypot(a=x[j]-x[i],b=y[j]-y[i])/2),s=1,t=atan2(b,a);c=0,u<9&&s+3;s-=2)for(a=x[i]+cos(b=t+s*u),b=y[i]+sin(b),k=n;k--;)hypot(a-x[k],b-y[k])<1.1&&++c>m?m=c:0;}
      |                                                           ^~~~~
main.c:1:59: note: include '<stdio.h>' or provide a declaration of 'scanf'
main.c:1:80: error: implicit declaration of function 'printf' [-Wimplicit-function-declaration]
    1 | double x[100],y[100],t,u,a,b,s;n,i,j,k,c,z;main(m){for(;m=scanf("%d",&n),z=i=n;printf("%d\n",m)){for(;!z?j=--i:scanf("%lf,%lf",x+z,y+--z))for(;!z&&j--;)for(u=acos(hypot(a=x[j]-x[i],b=y[j]-y[i])/2),s=1,t=atan2(b,a);c=0,u<9&&s+3;s-=2)for(a=x[i]+cos(b=t+s*u),b=y[i]+sin(b),k=n;k--;)hypot(a-x[k],b-y[k])<1.1&&++c>m?m=c:0;}
      |                                                                                ^~~~~~
main.c:1:80: note: include '<stdio.h>' or provide a declaration of 'printf'
main.c:1:80: warning: incompatible implicit declaration of built-in function 'printf' [-Wbuiltin-declaration-mismatch]
main.c:1:80: note: include '<stdio.h>' or provide a declaration of 'printf'
main.c:1:138: error: expected ';' before ')' token
    1 | double x[100],y[100],t,u,a,b,s;n,i,j,k,c,z;main(m){for(;m=scanf("%d",&n),z=i=n;printf("%d\n",m)){for(;!z?j=--i:scanf("%lf,%lf",x+z,y+--z))for(;!z&&j--;)for(u=acos(hypot(a=x[j]-x[i],b=y[j]-y[i])/2),s=1,t=atan2(b,a);c=0,u<9&&s+3;s-=2)for(a=x[i]+cos(b=t+s*u),b=y[i]+sin(b),k=n;k--;)hypot(a-x[k],b-y[k])<1.1&&++c>m?m=c:0;}
      |                                                                                                                                          ^
      |                                                                                                                                          ;
main.c:1:159: error: implicit declaration of function 'acos' [-Wimplicit-function-declaration]
    1 | double x[100],y[100],t,u,a,b,s;n,i,j,k,c,z;main(m){for(;m=scanf("%d",&n),z=i=n;printf("%d\n",m)){for(;!z?j=--i:scanf("%lf,%lf",x+z,y+--z))for(;!z&&j--;)for(u=acos(hypot(a=x[j]-x[i],b=y[j]-y[i])/2),s=1,t=atan2(b,a);c=0,u<9&&s+3;s-=2)for(a=x[i]+cos(b=t+s*u),b=y[i]+sin(b),k=n;k--;)hypot(a-x[k],b-y[k])<1.1&&++c>m?m=c:0;}
      |                                                                                                                                                               ^~~~
main.c:1:1: note: include '<math.h>' or provide a declaration of 'acos'
  +++ |+#include <math.h>
    1 | double x[100],y[100],t,u,a,b,s;n,i,j,k,c,z;main(m){for(;m=scanf("%d",&n),z=i=n;printf("%d\n",m)){for(;!z?j=--i:scanf("%lf,%lf",x+z,y+--z))for(;!z&&j--;)for(u=acos(hypot(a=x[j]-x[i],b=y[j]-y[i])/2),s=1,t=atan2(b,a);c=0,u<9&&s+3;s-=2)for(a=x[i]+cos(b=t+s*u),b=y[i]+sin(b),k=n;k--;)hypot(a-x[k],b-y[k])<1.1&&++c>m?m=c:0;}
main.c:1:159: warning: incompatible implicit declaration of built-in function 'acos' [-Wbuiltin-declaration-mismatch]
    1 | double x[100],y[100],t,u,a,b,s;n,i,j,k,c,z;main(m){for(;m=scanf("%d",&n),z=i=n;printf("%d\n",m)){for(;!z?j=--i:scanf("%lf,%lf",x+z,y+--z))for(;!z&&j--;)for(u=acos(hypot(a=x[j]-x[i],b=y[j]-y[i])/2),s=1,t=atan2(b,a);c=0,u<9&&s+3;s-=2)for(a=x[i]+cos(b=t+s*u),b=y[i]+sin(b),k=n;k--;)hypot(a-x[k],b-y[k])<1.1&&++c>m?m=c:0;}
      |                                                                                                                                                               ^~~~
main.c:1:159: note: include '<math.h>' or provide a declaration of 'acos'
main.c:1:164: error: implicit declaration of function 'hypot' [-Wimplicit-function-declaration]
    1 | double x[100],y[100],t,u,a,b,s;n,i,j,k,c,z;main(m){for(;m=scanf("%d",&n),z=i=n;printf("%d\n",m)){for(;!z?j=--i:scanf("%lf,%lf",x+z,y+--z))for(;!z&&j--;)for(u=acos(hypot(a=x[j]-x[i],b=y[j]-y[i])/2),s=1,t=atan2(b,a);c=0,u<9&&s+3;s-=2)for(a=x[i]+cos(b=t+s*u),b=y[i]+sin(b),k=n;k--;)hypot(a-x[k],b-y[k])<1.1&&++c>m?m=c:0;}
      |                                                                                                                                                                    ^~~~~
main.c:1:164: note: include '<math.h>' or provide a declaration of 'hypot'
main.c:1:164: warning: incompatible implicit declaration of built-in function 'hypot' [-Wbuiltin-declaration-mismatch]
main.c:1:164: note: include '<math.h>' or provide a declaration of 'hypot'
main.c:1:204: error: implicit declaration of function 'atan2' [-Wimplicit-function-declaration]
    1 | double x[100],y[100],t,u,a,b,s;n,i,j,k,c,z;main(m){for(;m=scanf("%d",&n),z=i=n;printf("%d\n",m)){for(;!z?j=--i:scanf("%lf,%lf",x+z,y+--z))for(;!z&&j--;)for(u=acos(hypot(a=x[j]-x[i],b=y[j]-y[i])/2),s=1,t=atan2(b,a);c=0,u<9&&s+3;s-=2)for(a=x[i]+cos(b=t+s*u),b=y[i]+sin(b),k=n;k--;)hypot(a-x[k],b-y[k])<1.1&&++c>m?m=c:0;}
      |                                                                                                                                                                                                            ^~~~~
main.c:1:204: note: include '<math.h>' or provide a declaration of 'atan2'
main.c:1:204: warning: incompatible implicit declaration of built-in function 'atan2' [-Wbuiltin-declaration-mismatch]
main.c:1:204: note: include '<math.h>' or provide a declaration of 'atan2'
main.c:1:244: error: implicit declaration of function 'cos' [-Wimplicit-function-declaration]
    1 | double x[100],y[100],t,u,a,b,s;n,i,j,k,c,z;main(m){for(;m=scanf("%d",&n),z=i=n;printf("%d\n",m)){for(;!z?j=--i:scanf("%lf,%lf",x+z,y+--z))for(;!z&&j--;)for(u=acos(hypot(a=x[j]-x[i],b=y[j]-y[i])/2),s=1,t=atan2(b,a);c=0,u<9&&s+3;s-=2)for(a=x[i]+cos(b=t+s*u),b=y[i]+sin(b),k=n;k--;)hypot(a-x[k],b-y[k])<1.1&&++c>m?m=c:0;}
      |