Language: C

t[55],y[55],n,x,z,i;
main(){
	for(;n-2||!z++;){
		for(i=1;i<2||getchar()==44;scanf("%d",y+i++));
		if(i>n)
			for(n=i;--i;t[i]=y[i]+fmax(t[i],t[i-1]);
		else
			for(n=i,i=0;i++<n;t[i]=y[i]+fmax(t[i],t[i+1]);
	}
	n=!printf("%d\n",t[1]);
}

Compiler output:
main.c:1:1: warning: data definition has no type or storage class
    1 | t[55],y[55],n,x,z,i;
      | ^
main.c:1:1: error: type defaults to 'int' in declaration of 't' [-Wimplicit-int]
main.c:1:7: error: type defaults to 'int' in declaration of 'y' [-Wimplicit-int]
    1 | t[55],y[55],n,x,z,i;
      |       ^
main.c:1:13: error: type defaults to 'int' in declaration of 'n' [-Wimplicit-int]
    1 | t[55],y[55],n,x,z,i;
      |             ^
main.c:1:15: error: type defaults to 'int' in declaration of 'x' [-Wimplicit-int]
    1 | t[55],y[55],n,x,z,i;
      |               ^
main.c:1:17: error: type defaults to 'int' in declaration of 'z' [-Wimplicit-int]
    1 | t[55],y[55],n,x,z,i;
      |                 ^
main.c:1:19: error: type defaults to 'int' in declaration of 'i' [-Wimplicit-int]
    1 | t[55],y[55],n,x,z,i;
      |                   ^
main.c:2:1: error: return type defaults to 'int' [-Wimplicit-int]
    2 | main(){
      | ^~~~
main.c: In function 'main':
main.c:4:30: error: implicit declaration of function 'getchar' [-Wimplicit-function-declaration]
    4 |                 for(i=1;i<2||getchar()==44;scanf("%d",y+i++));
      |                              ^~~~~~~
main.c:1:1: note: 'getchar' is defined in header '<stdio.h>'; this is probably fixable by adding '#include <stdio.h>'
  +++ |+#include <stdio.h>
    1 | t[55],y[55],n,x,z,i;
main.c:4:44: error: implicit declaration of function 'scanf' [-Wimplicit-function-declaration]
    4 |                 for(i=1;i<2||getchar()==44;scanf("%d",y+i++));
      |                                            ^~~~~
main.c:4:44: note: include '<stdio.h>' or provide a declaration of 'scanf'
main.c:4:44: warning: incompatible implicit declaration of built-in function 'scanf' [-Wbuiltin-declaration-mismatch]
main.c:4:44: note: include '<stdio.h>' or provide a declaration of 'scanf'
main.c:6:47: error: implicit declaration of function 'fmax' [-Wimplicit-function-declaration]
    6 |                         for(n=i;--i;t[i]=y[i]+fmax(t[i],t[i-1]);
      |                                               ^~~~
main.c:1:1: note: include '<math.h>' or provide a declaration of 'fmax'
  +++ |+#include <math.h>
    1 | t[55],y[55],n,x,z,i;
main.c:6:47: warning: incompatible implicit declaration of built-in function 'fmax' [-Wbuiltin-declaration-mismatch]
    6 |                         for(n=i;--i;t[i]=y[i]+fmax(t[i],t[i-1]);
      |                                               ^~~~
main.c:6:47: note: include '<math.h>' or provide a declaration of 'fmax'
main.c:6:64: error: expected ')' before ';' token
    6 |                         for(n=i;--i;t[i]=y[i]+fmax(t[i],t[i-1]);
      |                            ~                                   ^
      |                                                                )
main.c:11:1: error: expected expression before '}' token
   11 | }
      | ^
main.c:11:1: error: expected declaration or statement at end of input