View Compilation Error

0_0_23280833_288.cpp: In function 'int main()':
0_0_23280833_288.cpp:21:5: error: 's' was not declared in this scope
     s+=(log10(i));
     ^
0_0_23280833_288.cpp:23:23: error: 's' was not declared in this scope
    printf("%d\n",(int)s+1);
                       ^