/in/foo.cc: In function 'int main()':
/in/foo.cc:11:16: warning: format '%d' expects argument of type 'int*', but argument 2 has type 'long long int*' [-Wformat=]
   scanf("%d",&n);
                ^
/in/foo.cc:12:37: warning: format '%d' expects argument of type 'int*', but argument 2 has type 'long long int*' [-Wformat=]
   for (j=1;j<=n;++j)scanf("%d",&a[j]);
                                     ^
/in/foo.cc:14:3: warning: this 'for' clause does not guard... [-Wmisleading-indentation]
   for (j=1;j<=a[n]*2;++j)f[j]=0;f[0]=1;
   ^~~
/in/foo.cc:14:33: note: ...this statement, but the latter is misleadingly indented as if it is guarded by the 'for'
   for (j=1;j<=a[n]*2;++j)f[j]=0;f[0]=1;
                                 ^