View Compilation Error

0_0_18774078_3092.cpp: In function 'int qaq(int)':
0_0_18774078_3092.cpp:6:19: error: 'gcd' was not declared in this scope
         if(gcd(i,a)>1)
                   ^
0_0_18774078_3092.cpp: In function 'int gcd(int, int)':
0_0_18774078_3092.cpp:19:18: error: 'abs' was not declared in this scope
         c=abs(a-b);
                  ^