/in/foo.cc: In function 'int main()':
/in/foo.cc:6:15: warning: format '%d' expects argument of type 'int*', but argument 2 has type 'long long int*' [-Wformat=]
  scanf("%d",&n);
               ^
/in/foo.cc:7:30: warning: format '%d' expects argument of type 'int', but argument 2 has type 'long long int' [-Wformat=]
  printf("%I64d",(n*(n+1))/2+1);
                              ^