View Compilation Error

0_0_24000540_8729.cpp:4:1: error: 'typdedef' does not name a type
 typdedef long long ll;
 ^
0_0_24000540_8729.cpp: In function 'int main()':
0_0_24000540_8729.cpp:9:27: error: 'll' was not declared in this scope
         cout<<ll(n*(n-1)/2)<<endl;
                           ^