int main()
{
    int a[300]={0},i=1,j,f=0,s=0;
    char p;
    for(i=0;scanf("%d",&a[i]);i++){
        if(getchar()=='\n')break;
    }
    i++;
    for(j=0;j<=i;j++){
    if(a[j]>f){s=f;f=a[j];}
        else if(a[j]<f&&a[j]>s){s=a[j];}
    }
    if(f==s||s==0)printf("No");
    else printf("%d",s);
    return 0;
}