/in/foo.cc:3:0: warning: ignoring #pragma optimize  [-Wunknown-pragmas]
 #pragma optimize(3, "Ofast", "inline")
 
/in/foo.cc: In function 'long long int read()':
/in/foo.cc:11:3: warning: this 'if' clause does not guard... [-Wmisleading-indentation]
   if (ch == '-') f = -1; ch = getchar();
   ^~
/in/foo.cc:11:26: note: ...this statement, but the latter is misleadingly indented as if it is guarded by the 'if'
   if (ch == '-') f = -1; ch = getchar();
                          ^~
/in/foo.cc: In function 'int main()':
/in/foo.cc:39:26: warning: iteration 1000003 invokes undefined behavior [-Waggressive-loop-optimizations]
         cnt[i] += cnt[i-1], cnt[i] %= mod;
                          ^
/in/foo.cc:38:23: note: within this loop
     for (int i = 2; i <= maxn; i++) {
                     ~~^~~~~~~
/in/foo.cc:32:19: warning: iteration 1000003 invokes undefined behavior [-Waggressive-loop-optimizations]
         if (!vis[i]) {
              ~~~~~^
/in/foo.cc:31:22: note: within this loop
     for (ll i = 2; i <= maxn; i++) {
                    ~~^~~~~~~