1#define FOO23#ifdef FOO4 int a;5 int b;6 #undef FOO7 #ifndef FOO8 int c;9 int d;10 #else11 int e;12 int f;13 #endif14 int e;15 int f;16 #ifdef FOO17 int c_;18 int d_;19 #else20 int e_;21 int f_;22 #endif23 int e_;24 int f_;25int26main()27{28 return 0;29}30#else31 int j;32 int k;33 #ifdef FOO34 int j;35 int k;36 #else37 int n;38 int o;39 #endif40 int n;41 int o;42 #ifndef FOO43 int r;44 int s;45 #else46 int t;47 int u;48 #endif49 int t;50 int u;51 #error bad branch52#endif