Language: C

A,B,a,b;main(n,S){for(;--n||scanf("%d",&n,A=B=A&&!printf(S,A,B))*n;a-b?(a>b?A:B)+=a+b:(A+=a,B+=b))scanf(S="%d %d\n",&a,&b);}

Compiler output:
main.c:1:1: warning: data definition has no type or storage class
    1 | A,B,a,b;main(n,S){for(;--n||scanf("%d",&n,A=B=A&&!printf(S,A,B))*n;a-b?(a>b?A:B)+=a+b:(A+=a,B+=b))scanf(S="%d %d\n",&a,&b);}
      | ^
main.c:1:1: error: type defaults to 'int' in declaration of 'A' [-Wimplicit-int]
main.c:1:3: error: type defaults to 'int' in declaration of 'B' [-Wimplicit-int]
    1 | A,B,a,b;main(n,S){for(;--n||scanf("%d",&n,A=B=A&&!printf(S,A,B))*n;a-b?(a>b?A:B)+=a+b:(A+=a,B+=b))scanf(S="%d %d\n",&a,&b);}
      |   ^
main.c:1:5: error: type defaults to 'int' in declaration of 'a' [-Wimplicit-int]
    1 | A,B,a,b;main(n,S){for(;--n||scanf("%d",&n,A=B=A&&!printf(S,A,B))*n;a-b?(a>b?A:B)+=a+b:(A+=a,B+=b))scanf(S="%d %d\n",&a,&b);}
      |     ^
main.c:1:7: error: type defaults to 'int' in declaration of 'b' [-Wimplicit-int]
    1 | A,B,a,b;main(n,S){for(;--n||scanf("%d",&n,A=B=A&&!printf(S,A,B))*n;a-b?(a>b?A:B)+=a+b:(A+=a,B+=b))scanf(S="%d %d\n",&a,&b);}
      |       ^
main.c:1:9: error: return type defaults to 'int' [-Wimplicit-int]
    1 | A,B,a,b;main(n,S){for(;--n||scanf("%d",&n,A=B=A&&!printf(S,A,B))*n;a-b?(a>b?A:B)+=a+b:(A+=a,B+=b))scanf(S="%d %d\n",&a,&b);}
      |         ^~~~
main.c: In function 'main':
main.c:1:9: error: type of 'n' defaults to 'int' [-Wimplicit-int]
main.c:1:9: error: type of 'S' defaults to 'int' [-Wimplicit-int]
main.c:1:29: error: implicit declaration of function 'scanf' [-Wimplicit-function-declaration]
    1 | A,B,a,b;main(n,S){for(;--n||scanf("%d",&n,A=B=A&&!printf(S,A,B))*n;a-b?(a>b?A:B)+=a+b:(A+=a,B+=b))scanf(S="%d %d\n",&a,&b);}
      |                             ^~~~~
main.c:1:1: note: include '<stdio.h>' or provide a declaration of 'scanf'
  +++ |+#include <stdio.h>
    1 | A,B,a,b;main(n,S){for(;--n||scanf("%d",&n,A=B=A&&!printf(S,A,B))*n;a-b?(a>b?A:B)+=a+b:(A+=a,B+=b))scanf(S="%d %d\n",&a,&b);}
main.c:1:29: warning: incompatible implicit declaration of built-in function 'scanf' [-Wbuiltin-declaration-mismatch]
    1 | A,B,a,b;main(n,S){for(;--n||scanf("%d",&n,A=B=A&&!printf(S,A,B))*n;a-b?(a>b?A:B)+=a+b:(A+=a,B+=b))scanf(S="%d %d\n",&a,&b);}
      |                             ^~~~~
main.c:1:29: note: include '<stdio.h>' or provide a declaration of 'scanf'
main.c:1:51: error: implicit declaration of function 'printf' [-Wimplicit-function-declaration]
    1 | A,B,a,b;main(n,S){for(;--n||scanf("%d",&n,A=B=A&&!printf(S,A,B))*n;a-b?(a>b?A:B)+=a+b:(A+=a,B+=b))scanf(S="%d %d\n",&a,&b);}
      |                                                   ^~~~~~
main.c:1:51: note: include '<stdio.h>' or provide a declaration of 'printf'
main.c:1:51: warning: incompatible implicit declaration of built-in function 'printf' [-Wbuiltin-declaration-mismatch]
main.c:1:51: note: include '<stdio.h>' or provide a declaration of 'printf'
main.c:1:58: error: passing argument 1 of 'printf' makes pointer from integer without a cast [-Wint-conversion]
    1 | A,B,a,b;main(n,S){for(;--n||scanf("%d",&n,A=B=A&&!printf(S,A,B))*n;a-b?(a>b?A:B)+=a+b:(A+=a,B+=b))scanf(S="%d %d\n",&a,&b);}
      |                                                          ^
      |                                                          |
      |                                                          int
main.c:1:58: note: expected 'const char *' but argument is of type 'int'
main.c:1:81: error: lvalue required as left operand of assignment
    1 | A,B,a,b;main(n,S){for(;--n||scanf("%d",&n,A=B=A&&!printf(S,A,B))*n;a-b?(a>b?A:B)+=a+b:(A+=a,B+=b))scanf(S="%d %d\n",&a,&b);}
      |                                                                                 ^~
main.c:1:106: error: assignment to 'int' from 'char *' makes integer from pointer without a cast [-Wint-conversion]
    1 | A,B,a,b;main(n,S){for(;--n||scanf("%d",&n,A=B=A&&!printf(S,A,B))*n;a-b?(a>b?A:B)+=a+b:(A+=a,B+=b))scanf(S="%d %d\n",&a,&b);}
      |                                                                                                          ^
main.c:1:106: error: passing argument 1 of 'scanf' makes pointer from integer without a cast [-Wint-conversion]
    1 | A,B,a,b;main(n,S){for(;--n||scanf("%d",&n,A=B=A&&!printf(S,A,B))*n;a-b?(a>b?A:B)+=a+b:(A+=a,B+=b))scanf(S="%d %d\n",&a,&b);}
      |                                                                                                         ~^~~~~~~~~~
      |                                                                                                          |
      |                                                                                                          int
main.c:1:106: note: expected 'const char *' but argument is of type 'int'