/in/foo.cc: In function 'int main()':
/in/foo.cc:10:9: warning: suggest parentheses around '-' inside '<<' [-Wparentheses]
   m=1<<n-1;
        ~^~
/in/foo.cc:13:13: warning: operation on 'ss' may be undefined [-Wsequence-point]
   s[ss++]=ss=0;
           ~~^~