View Compilation Error

0_0_33508215_8123.cpp: In function 'int main()':
0_0_33508215_8123.cpp:10:12: error: 'mod' was not declared in this scope
         a%=mod;
            ^
0_0_33508215_8123.cpp: In function 'int main()':
0_0_33508215_8123.cpp:22:5: error: redefinition of 'int main()'
 int main()
     ^
0_0_33508215_8123.cpp:4:5: note: 'int main()' previously defined here
 int main()
     ^