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| #include <cstdio>
#include <stack>
using namespace std;
typedef long long LL;
const int N = 15;
LL f[N], p[N], num[N], ans[N];
void init()
{
p[0] = 1;
for (int i = 1; i < N; i++)
{
f[i] = f[i - 1] * 10 + p[i - 1];
p[i] = p[i - 1] * 10;
}
}
void solve(int x)
{
int tmp = x;
int idx = 0;
while (tmp)
{
num[++idx] = tmp % 10;
tmp /= 10;
}
for (int i = idx; i; i--)
{
for (int j = 0; j < 10; j++)
ans[j] += f[i - 1] * num[i];
for (int j = 0; j < num[i]; j++)
ans[j] += p[i - 1];
x -= p[i - 1] * num[i];
ans[num[i]] += x + 1;
ans[0] -= p[i - 1];
}
}
int main()
{
init();
int n;
scanf("%d", &n);
solve(n);
LL res = 0;
for (int i = 0; i < 10; i++)
res += i * ans[i];
printf("%lld", res);
return 0;
}
|