View Compilation Error

0_0_24578546_29883.cpp: In function 'int main()':
0_0_24578546_29883.cpp:36:36: error: too many arguments to function 'll gcd(ll, ll)'
             ll ans=qpow(a,gcd(m,n,k))-1;
                                    ^
0_0_24578546_29883.cpp:8:4: note: declared here
 ll gcd(ll a,ll b)
    ^
0_0_24578546_29883.cpp:36:37: error: too few arguments to function 'll qpow(ll, ll, ll)'
             ll ans=qpow(a,gcd(m,n,k))-1;
                                     ^
0_0_24578546_29883.cpp:15:4: note: declared here
 ll qpow(ll a,ll b,ll c)//a的b次方对c取余
    ^