帮忙看一下下，谢谢

#include <stdio.h>

int main(void){

char a[14], mod[12] = "0123456789X";

gets(a);

int i, j = 1, t = 0;

for(i = 0; i < 12; i++) {

if(a[i] == '-') continue;

t += (a[i]-'1')*j++;

}

if(mod[t%11] == a[12]) printf("Right");

else {

a[12] = mod[t%11];

puts(a);

}

return 0;

}