/in/foo.cc: In function 'int main()':
/in/foo.cc:7:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(int i=1;i<strlen(a);i++){
                ^
/in/foo.cc:9:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
    for(int j=1;j<strlen(a);j++) a[j-1]=a[j];
                 ^