#include<stdio.h>

int main(){
    int n,x;
    int sum=0;
    scanf("%d",&n);
    
    do{
        x=n%10;
        n=n/10;
        sum=sum*10+x;
    }while(n!=0);
    
    
    
    printf("%03d",sum);
    
}

实在看不出来有啥问题，求大佬指正