C++ :

#include <cstdio>
/* 找所有 <=6 位、数位和 == n 的回文数，从小到大输出；没有则 -1 */
static int num[8];
int main(){
    int n; if(scanf("%d", &n) != 1) return 0;
    int found = 0;
    for(int x = 1; x <= 999999; x++){
        int d[8], L = 0, t = x;
        while(t){ d[L++] = t % 10; t /= 10; }
        int ok = 1, s = 0;
        for(int i=0, j=L-1; i<j; i++, j--) if(d[i] != d[j]){ ok = 0; break; }
        if(!ok) continue;
        for(int i=0;i<L;i++) s += d[i];
        if(s != n) continue;
        if(found) putchar('\n');
        printf("%d", x);
        found = 1;
    }
    if(!found) printf("-1\n");
    else putchar('\n');
    return 0;
}