foo.cc: In function 'int main()':
foo.cc:6:10: error: expected unqualified-id before numeric constant
  int n,m,1;
          ^
foo.cc:7:13: error: 'i' was not declared in this scope
  cin>>n>>m>>i;
             ^
foo.cc:8:13: warning: suggest parentheses around assignment used as truth value [-Wparentheses]
  for(int i;i=2;i<=m)
            ~^~
foo.cc:8:17: warning: for increment expression has no effect [-Wunused-value]
  for(int i;i=2;i<=m)
                ~^~~

自豪的采用HydroJudge(https://github.com/hydro-dev/Hydro)进行评测。