纯水
#include#include int n;int bet[10000+5];int input[100000+5];int main(){ //freopen("in.txt","r",stdin); scanf("%d",&n); memset(bet, 0, sizeof(bet)); for(int i = 0; i < n; i++){ int tmp; scanf("%d",&tmp); input[i] = tmp; bet[tmp]++; } for(int i = 0; i < n; i++){ int tmp = input[i]; if(bet[tmp] == 1){//只出现1次 printf("%d",tmp); return 0; } } printf("None"); return 0;}