View Compilation Error

0_0_38374240_13459.cpp: In function 'int main()':
0_0_38374240_13459.cpp:57:17: error: expected initializer before 'a'
     char string a[N],b[N];
                 ^
0_0_38374240_13459.cpp:65:24: error: 'a' was not declared in this scope
             scanf("%s",a[i]);
                        ^
0_0_38374240_13459.cpp:67:24: error: 'b' was not declared in this scope
             scanf("%s",b[i]);
                        ^
0_0_38374240_13459.cpp:69:23: error: 'a' was not declared in this scope
                  if(M[a[j][0]]+M[a[j][1]]<M[b[i][0]]+M[b[i][1]])
                       ^