foo.cpp: In function 'int main()':
foo.cpp:20:9: error: 'read' was not declared in this scope
  n=read();
         ^
foo.cpp:31:23: warning: format '%d' expects argument of type 'int', but argument 2 has type 'long long int' [-Wformat=]
  printf("%d\n",f[1][n]);
                       ^