/in/foo.cc:3:7: error: 'i' was not declared in this scope
 int F[i][j],n,a[1000],sum;
       ^
/in/foo.cc:3:10: error: 'j' was not declared in this scope
 int F[i][j],n,a[1000],sum;
          ^
/in/foo.cc: In function 'int main()':
/in/foo.cc:6:9: error: 'F' was not declared in this scope
  memset(F,-999999,sizeof(F));
         ^