zoj 1476 Weird Clock

#include <stdio.h>#include <string.h>int main(){int s,d,i,sum;int flag[60];while(scanf("%d%d",&s,&d)!=EOF){sum=s;i=0;if(s==0&&d==0) break;memset(flag,0,sizeof(flag));while(1){s=(s+s*d)%60;i++;flag[s]++;if(s==0) break;if(flag[s]==2) break;}if(s==0) printf("%dn",i);else printf("Impossiblen");}return 0;}