View Compilation Error

0_0_14723955_29298.cpp: In function 'void solve()':
0_0_14723955_29298.cpp:13:27: error: 'sum2' was not declared in this scope
             sum += s1[i], sum2 += s2[i];
                           ^
0_0_14723955_29298.cpp:14:22: error: 'sum2' was not declared in this scope
         if(abs(sum - sum2)&1) sum = 1;
                      ^