View Compilation Error

0_0_22941267_10394.cpp:3:10: error: 'b' was not declared in this scope
 int mm(a>b?a-b:0);
          ^
0_0_22941267_10394.cpp:3:14: error: 'b' was not declared in this scope
 int mm(a>b?a-b:0);
              ^
0_0_22941267_10394.cpp: In function 'int main()':
0_0_22941267_10394.cpp:19:31: error: 'mm' cannot be used as a function
      ans+=mm(a[i][j],a[i][j+1]);
                               ^
0_0_22941267_10394.cpp:24:31: error: 'mm' cannot be used as a function
      ans+=mm(a[i][j],a[i][j-1]);
                               ^
0_0_22941267_10394.cpp:29:31: error: 'mm' cannot be used as a function
      ans+=mm(a[i][j],a[i+1][j]);
                               ^
0_0_22941267_10394.cpp:34:31: error: 'mm' cannot be used as a function
      ans+=mm(a[i][j],a[i-1][j]);
                               ^