/in/foo.cc: In function 'int work()':
/in/foo.cc:33:21: warning: iteration 1000001 invokes undefined behavior [-Waggressive-loop-optimizations]
   f[i][0] = f[i-1][0] + tem;
             ~~~~~~~~^
/in/foo.cc:9:43: note: within this loop
 #define F(i, x, y) for(register int i=x; i<=y; i++)
/in/foo.cc:32:4:
  F(i, 5, 1000010) {
    ~~~~~~~                                 
/in/foo.cc:32:2: note: in expansion of macro 'F'
  F(i, 5, 1000010) {
  ^
/in/foo.cc:38:21: warning: iteration 999998 invokes undefined behavior [-Waggressive-loop-optimizations]
   f[i][1] = f[i-1][1] + tem;
             ~~~~~~~~^
/in/foo.cc:9:43: note: within this loop
 #define F(i, x, y) for(register int i=x; i<=y; i++)
/in/foo.cc:37:4:
  F(i, 8, 1000010) {
    ~~~~~~~                                 
/in/foo.cc:37:2: note: in expansion of macro 'F'
  F(i, 8, 1000010) {
  ^