View Compilation Error

0_0_18352836_14603.cpp: In function 'int main()':
0_0_18352836_14603.cpp:37:59: error: 'ch' was not declared in this scope
    for(scanf("%s",s1),j=0,x=1,len=strlen(s1);j<len;x=a[x][ch],j++)
                                                           ^
0_0_18352836_14603.cpp:46:9: error: 'ch' was not declared in this scope
    for (ch=s2[j]-'a';!a[x][ch];x=fail[x]);
         ^
0_0_18352836_14603.cpp:47:13: error: 'ch' was not declared in this scope
    x = a[x][ch];
             ^