void main()
{int a[301],b=0,c,d=0,i,j;char s;
for(i=1;i<=300;i++)
{scanf("%d",&a[i]);b=b+1;scanf("%c",&s);if(s!=',') break;}
for(i=1;i<=b;i++)
{for(j=i;j<=b;j++) {if(a[i]!=a[j]) d=1;
	if(a[j]>a[i]){c=a[i];a[i]=a[j];a[j]=c;}}}
if((d==0)||(b==1)) printf("No\n");
for(i=2;i<=b;i++) {if(a[i]!=a[1]){printf("%d\n",a[i]);break;}}
}
