/in/foo.cc: In function 'void init()':
/in/foo.cc:19:70: warning: suggest parentheses around '-' inside '<<' [-Wparentheses]
   19 |                                 f[i][j] = max(f[i][j-1],f[i + (1 << j-1)][j - 1]);
      |                                                                     ~^~