/* 2195 */

 #include <cstdio>

 #include <cstring>

 #include <cstdlib>

 #define MAXN 1000

 #define MAXL 205

 #define INF  0xfffffff

 int dp[MAXL][MAXN+];

 char s[MAXL];

 int main() {

     int len;

     int i, j, k;

     int bi, tmp;

     double ans;

     #ifndef ONLINE_JUDGE

         freopen("data.in", "r", stdin);

     #endif

     while (scanf("%s", s) != EOF) {

         len = strlen(s);

         bi = (s[]=='') ? :MAXN;

         for (j=; j<=MAXN; ++j) {

             dp[][j] = (j-bi)*(j-bi);

         }

         for (i=; i<len; ++i) {

             bi = (s[i]=='') ? :MAXN;

             tmp = INF;

             for (j=; j<=MAXN; ++j) {

                 if (dp[i-][j] < tmp)

                     tmp = dp[i-][j];

                 dp[i][j] = tmp + (j-bi)*(j-bi);

             }

         }

         tmp = INF;

         i = len-;

         for (j=; j<=MAXN; ++j)

             if (dp[i][j] < tmp)

                 tmp = dp[i][j];

         ans = tmp / 1000000.0;

         printf("%.3lf\n", ans);

     }

     return ;

 }