View Compilation Error

0_0_26833590_20054.cpp: In function 'void solve()':
0_0_26833590_20054.cpp:89:10: error: 'm' was not declared in this scope
  For(i,1,m-1) o=(o+ch[i])/2;
          ^
0_0_26833590_20054.cpp:16:35: note: in definition of macro 'For'
 #define For(i,a,b) for(int i=a;i<=b;i++) 
                                   ^
0_0_26833590_20054.cpp:91:10: error: 'm' was not declared in this scope
  For(i,0,m-1) {
          ^
0_0_26833590_20054.cpp:16:35: note: in definition of macro 'For'
 #define For(i,a,b) for(int i=a;i<=b;i++) 
                                   ^