View Compilation Error

0_0_28591120_782.cpp: In function 'int main()':
0_0_28591120_782.cpp:7:4: error: 'a' was not declared in this scope
 if(a>b)z=a;
    ^
0_0_28591120_782.cpp:7:6: error: 'b' was not declared in this scope
 if(a>b)z=a;
      ^