View Compilation Error

0_0_30316849_26638.cpp: In function 'int main()':
0_0_30316849_26638.cpp:69:33: error: invalid conversion from 'char' to 'char*' [-fpermissive]
                   s=strcat(a[i-1],b[j-1]);
                                 ^
In file included from GCC4.9.2/x86_64-w64-mingw32/include/c++/cstring:42:0,
                 from 0_0_30316849_26638.cpp:7:
GCC4.9.2/x86_64-w64-mingw32/include/string.h:52:18: note: initializing argument 1 of 'char* strcat(char*, const char*)'
   char * __cdecl strcat(char * __restrict__ _Dest,const char * __restrict__ _Source);
                  ^
0_0_30316849_26638.cpp:69:40: error: invalid conversion from 'char' to 'const char*' [-fpermissive]
                   s=strcat(a[i-1],b[j-1]);
                                        ^
In file included from GCC4.9.2/x86_64-w64-mingw32/include/c++/cstring:42:0,
                 from 0_0_30316849_26638.cpp:7:
GCC4.9.2/x86_64-w64-mingw32/include/string.h:52:18: note: initializing argument 2 of 'char* strcat(char*, const char*)'
   char * __cdecl strcat(char * __restrict__ _Dest,const char * __restrict__ _Source);
                  ^