/in/foo.cc: In function 'int main()':
/in/foo.cc:18:24: warning: suggest parentheses around '-' inside '<<' [-Wparentheses]
  for(int i=1;i<=n-(1<<j-1);i++)
                       ~^~
/in/foo.cc:19:33: warning: suggest parentheses around '-' inside '<<' [-Wparentheses]
  f[i][j]=max(f[i][j-1],f[i+(1<<j-1)][j-1]);
                                ~^~