can anyone plz explain this

Question

int main(void)
{
int val1=11, val2=22, val3=33;

val3 = (val2++),val1++,val2++ ;
val1 = val3++,val2++,val3++;
val2 = ((val1--,--val3),--val1) ;

printf("val1=%d val2=%d val3=%d",val1,val2,val3);
return 0;
}