/in/foo.cc: In function 'int main()':
/in/foo.cc:23:43: warning: operation on 'py' may be undefined [-Wsequence-point]
   if(temp=='S')sum=sum+sumy[py]-(n-sumy[py++]);
                                         ~~^~
/in/foo.cc:24:30: warning: operation on 'py' may be undefined [-Wsequence-point]
   if(temp=='J') sum=sum-sumy[--py]+(n-sumy[py]);
                              ^~~~
/in/foo.cc:25:44: warning: operation on 'px' may be undefined [-Wsequence-point]
   if(temp=='I') sum=sum+sumx[px]-(n-sumx[px++]);
                                          ~~^~
/in/foo.cc:26:30: warning: operation on 'px' may be undefined [-Wsequence-point]
   if(temp=='Z') sum=sum-sumx[--px]+(n-sumx[px]);
                              ^~~~