View Compilation Error

0_0_17975504_15200.cpp: In function 'int main()':
0_0_17975504_15200.cpp:74:17: error: 'z' was not declared in this scope
             x=0,z=0;
                 ^
0_0_17975504_15200.cpp:76:27: error: 'Ria' was not declared in this scope
             F(i,0,n) Ria(a),x+=a;
                           ^