View Compilation Error

0_0_29263553_26712.cpp: In function 'int main(int, const char**)':
0_0_29263553_26712.cpp:56:9: error: redeclaration of 'int k'
     int k=s1.size();
         ^
0_0_29263553_26712.cpp:53:9: note: 'int k' previously declared here
     int k=s2.top();
         ^