/in/foo.c:1:6: warning: return type of 'main' is not 'int' [-Wmain]
 void main()
      ^~~~
/in/foo.c: In function 'main':
/in/foo.c:7:42: warning: implicit declaration of function 'printf' [-Wimplicit-function-declaration]
 if(i*5+j*3+k/3==100&&k%3==0&&i+j+k==100) printf("%d, %d, %d\n", i, j, k);
                                          ^~~~~~
/in/foo.c:7:42: warning: incompatible implicit declaration of built-in function 'printf'
/in/foo.c:7:42: note: include '<stdio.h>' or provide a declaration of 'printf'