/in/foo.cc: In function 'long long int read()':
/in/foo.cc:19:15: warning: 's' may be used uninitialized in this function [-Wmaybe-uninitialized]
   while(s>'9' || s<'0'){s=getchar();if(s=='-') sym=-1;}
         ~~~~~~^~~~~~~~
/in/foo.cc: In function 'int main()':
/in/foo.cc:19:15: warning: 's' may be used uninitialized in this function [-Wmaybe-uninitialized]
   while(s>'9' || s<'0'){s=getchar();if(s=='-') sym=-1;}
         ~~~~~~^~~~~~~~
/in/foo.cc:18:8: note: 's' was declared here
   char s;
        ^
/in/foo.cc:19:15: warning: 's' may be used uninitialized in this function [-Wmaybe-uninitialized]
   while(s>'9' || s<'0'){s=getchar();if(s=='-') sym=-1;}
         ~~~~~~^~~~~~~~
/in/foo.cc:18:8: note: 's' was declared here
   char s;
        ^