View Compilation Error

0_0_17714428_14129.cpp:4:1: error: 'll' does not name a type
 ll gcd(ll a,ll b){return b?gcd(b,a%b):a;}
 ^
0_0_17714428_14129.cpp: In function 'int main()':
0_0_17714428_14129.cpp:31:26: error: 'gcd' was not declared in this scope
         y=gcd(fenzi,fenmu);
                          ^