/in/foo.cc: In function 'int main()':
/in/foo.cc:20:16: error: expected ')' before ']' token
         f[(1<<i][i+1]=0;
                ^
/in/foo.cc:20:24: error: expected ']' before ';' token
         f[(1<<i][i+1]=0;
                        ^
/in/foo.cc:20:24: warning: statement has no effect [-Wunused-value]
         f[(1<<i][i+1]=0;
         ~~~~~~~~~~~~~~~^
/in/foo.cc:19:5: warning: this 'for' clause does not guard... [-Wmisleading-indentation]
     for(int i=0;i<n;i++)
     ^~~
/in/foo.cc:21:2: note: ...this statement, but the latter is misleadingly indented as if it is guarded by the 'for'
  for(int i=1;i<(1<<n);i++)
  ^~~