Language: C

s,n,i;main(x,y){fesetround(FE_TONEAREST);for(;~scanf("%d,%d",&x,&y)?s+=x*y:!printf("%d\n%.f\n",s,nearbyint(1.*n/i));i++)n+=y;}////

Compiler output:
main.c:1:1: warning: data definition has no type or storage class
    1 | s,n,i;main(x,y){fesetround(FE_TONEAREST);for(;~scanf("%d,%d",&x,&y)?s+=x*y:!printf("%d\n%.f\n",s,nearbyint(1.*n/i));i++)n+=y;}////
      | ^
main.c:1:1: error: type defaults to 'int' in declaration of 's' [-Wimplicit-int]
main.c:1:3: error: type defaults to 'int' in declaration of 'n' [-Wimplicit-int]
    1 | s,n,i;main(x,y){fesetround(FE_TONEAREST);for(;~scanf("%d,%d",&x,&y)?s+=x*y:!printf("%d\n%.f\n",s,nearbyint(1.*n/i));i++)n+=y;}////
      |   ^
main.c:1:5: error: type defaults to 'int' in declaration of 'i' [-Wimplicit-int]
    1 | s,n,i;main(x,y){fesetround(FE_TONEAREST);for(;~scanf("%d,%d",&x,&y)?s+=x*y:!printf("%d\n%.f\n",s,nearbyint(1.*n/i));i++)n+=y;}////
      |     ^
main.c:1:7: error: return type defaults to 'int' [-Wimplicit-int]
    1 | s,n,i;main(x,y){fesetround(FE_TONEAREST);for(;~scanf("%d,%d",&x,&y)?s+=x*y:!printf("%d\n%.f\n",s,nearbyint(1.*n/i));i++)n+=y;}////
      |       ^~~~
main.c: In function 'main':
main.c:1:7: error: type of 'x' defaults to 'int' [-Wimplicit-int]
main.c:1:7: error: type of 'y' defaults to 'int' [-Wimplicit-int]
main.c:1:17: error: implicit declaration of function 'fesetround' [-Wimplicit-function-declaration]
    1 | s,n,i;main(x,y){fesetround(FE_TONEAREST);for(;~scanf("%d,%d",&x,&y)?s+=x*y:!printf("%d\n%.f\n",s,nearbyint(1.*n/i));i++)n+=y;}////
      |                 ^~~~~~~~~~
main.c:1:28: error: 'FE_TONEAREST' undeclared (first use in this function)
    1 | s,n,i;main(x,y){fesetround(FE_TONEAREST);for(;~scanf("%d,%d",&x,&y)?s+=x*y:!printf("%d\n%.f\n",s,nearbyint(1.*n/i));i++)n+=y;}////
      |                            ^~~~~~~~~~~~
main.c:1:28: note: each undeclared identifier is reported only once for each function it appears in
main.c:1:48: error: implicit declaration of function 'scanf' [-Wimplicit-function-declaration]
    1 | s,n,i;main(x,y){fesetround(FE_TONEAREST);for(;~scanf("%d,%d",&x,&y)?s+=x*y:!printf("%d\n%.f\n",s,nearbyint(1.*n/i));i++)n+=y;}////
      |                                                ^~~~~
main.c:1:1: note: include '<stdio.h>' or provide a declaration of 'scanf'
  +++ |+#include <stdio.h>
    1 | s,n,i;main(x,y){fesetround(FE_TONEAREST);for(;~scanf("%d,%d",&x,&y)?s+=x*y:!printf("%d\n%.f\n",s,nearbyint(1.*n/i));i++)n+=y;}////
main.c:1:48: warning: incompatible implicit declaration of built-in function 'scanf' [-Wbuiltin-declaration-mismatch]
    1 | s,n,i;main(x,y){fesetround(FE_TONEAREST);for(;~scanf("%d,%d",&x,&y)?s+=x*y:!printf("%d\n%.f\n",s,nearbyint(1.*n/i));i++)n+=y;}////
      |                                                ^~~~~
main.c:1:48: note: include '<stdio.h>' or provide a declaration of 'scanf'
main.c:1:77: error: implicit declaration of function 'printf' [-Wimplicit-function-declaration]
    1 | s,n,i;main(x,y){fesetround(FE_TONEAREST);for(;~scanf("%d,%d",&x,&y)?s+=x*y:!printf("%d\n%.f\n",s,nearbyint(1.*n/i));i++)n+=y;}////
      |                                                                             ^~~~~~
main.c:1:77: note: include '<stdio.h>' or provide a declaration of 'printf'
main.c:1:77: warning: incompatible implicit declaration of built-in function 'printf' [-Wbuiltin-declaration-mismatch]
main.c:1:77: note: include '<stdio.h>' or provide a declaration of 'printf'
main.c:1:98: error: implicit declaration of function 'nearbyint' [-Wimplicit-function-declaration]
    1 | s,n,i;main(x,y){fesetround(FE_TONEAREST);for(;~scanf("%d,%d",&x,&y)?s+=x*y:!printf("%d\n%.f\n",s,nearbyint(1.*n/i));i++)n+=y;}////
      |                                                                                                  ^~~~~~~~~
main.c:1:1: note: include '<math.h>' or provide a declaration of 'nearbyint'
  +++ |+#include <math.h>
    1 | s,n,i;main(x,y){fesetround(FE_TONEAREST);for(;~scanf("%d,%d",&x,&y)?s+=x*y:!printf("%d\n%.f\n",s,nearbyint(1.*n/i));i++)n+=y;}////
main.c:1:98: warning: incompatible implicit declaration of built-in function 'nearbyint' [-Wbuiltin-declaration-mismatch]
    1 | s,n,i;main(x,y){fesetround(FE_TONEAREST);for(;~scanf("%d,%d",&x,&y)?s+=x*y:!printf("%d\n%.f\n",s,nearbyint(1.*n/i));i++)n+=y;}////
      |                                                                                                  ^~~~~~~~~
main.c:1:98: note: include '<math.h>' or provide a declaration of 'nearbyint'