/*Name: 拓扑排序，多次拓扑Copyright: Author: Try86Date: 16/04/12 21:36Description:
*/#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <iostream>using namespace std;const int N = 27;bool ch[N];
char ans[N]; //存拓扑序
int inDeg[N]; //入度数
struct node {int v;node *next;node(int vv, node *p) {v = vv;next = p;}
};struct graph {node *link;
}G[N];void init(int n) {for (int i=0; i<n; ++i) G[i].link = NULL;return ;
} void buildG(int u, int v) {node *p = new node(v, G[u].link);G[u].link = p;return ;
}int topoSort(int n, int s) {int temp[27], cs, j, k = 0;for (int i=0; i<n; ++i) temp[i] = inDeg[i];//当前各点入度数 bool flag = true;while (s--) {cs = 0;//统计入度为0的顶点个数 for (int i=0; i<n; ++i) {if (temp[i] == 0) j = i, ++cs;}if (cs >= 1) {if (cs > 1) flag = false;//入度为0的顶点个数大于1，拓扑序有多个，不能比较拓扑序的关系 for (node *p=G[j].link; p; p=p->next) --temp[p->v];ans[k++] = j + 'A';temp[j] = -1;ans[k] = '\0';}else return -1;//入度为0的个数为0，存在回路，不能形成拓扑序
    }if (flag) return k;return 0;
}void del(node *p) {if (!p) return ;del(p->next);delete p;return ;
}int main() {int n, m;char str[4];while (scanf("%d%d", &n, &m) && n+m) {init(n);memset(ch, false, sizeof(ch));memset(inDeg, 0, sizeof(inDeg));int  junge, counts, k;junge = counts = 0;for (int i=0; i<m; ++i) {scanf ("%s", str);if (junge != -1) {//junge!=-1,则当前输入下，不存在回路int u = str[0] - 'A';int v = str[2] - 'A';buildG(u, v);++inDeg[v];if (!ch[u]) ++counts, ch[u] = true;if (!ch[v]) ++counts, ch[v] = true;}if (junge == 0) {//junge==0,则当前输入下，不存在回路，也不存在孤立点，图连通，需继续拓扑 int t = topoSort(n, counts);if (t == -1) junge = -1, k = i + 1;else if (t == n) junge = 1, k = i + 1;}}if (junge == -1) printf ("Inconsistency found after %d relations.\n", k);else if (junge == 0) printf ("Sorted sequence cannot be determined.\n");else printf ("Sorted sequence determined after %d relations: %s.\n", k, ans); for (int i=0; i<n; ++i) del(G[i].link);}return 0;
}