/in/foo.cc:28:7: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
  main() {
       ^
/in/foo.cc: In function 'int main()':
/in/foo.cc:30:18: warning: unused variable 'pp' [-Wunused-variable]
  int t = 3,p = 4,pp = 4;
                  ^~
/in/foo.cc:45:9: warning: iteration 549996 invokes undefined behavior [-Waggressive-loop-optimizations]
    f[p] = f[p-1]+t;
    ~~~~~^~~~~~~~~~
/in/foo.cc:43:11: note: within this loop
   while(p < N) {
           ^
/in/foo.cc:37:9: warning: iteration 549997 invokes undefined behavior [-Waggressive-loop-optimizations]
    f[p] = f[p-1]+t;
    ~~~~~^~~~~~~~~~
/in/foo.cc:33:11: note: within this loop
   while(p < N) {
           ^