1's Compliments

#include<stdio.h>
int main()
{
    int i;
    char ibr[40];
    gets(ibr);
    int l=strlen(ibr);
   for(i=l-1; i>=0 ; i--)
   {
       if(ibr[i]=='1')
        ibr[i]='0';
     else  if(ibr[i]=='0')
            ibr[i]='1';
   }
   printf("%s",ibr);
   return 0;
}