View Compilation Error

0_0_21766956_24442.cpp: In function 'int main()':
0_0_21766956_24442.cpp:4:12: error: redeclaration of 'int s'
  int n,s,a,s;
            ^
0_0_21766956_24442.cpp:4:8: note: 'int s' previously declared here
  int n,s,a,s;
        ^
0_0_21766956_24442.cpp:8:7: error: 'i' was not declared in this scope
   for(i=0;i<n;i++)
       ^