1 #include <cstdio> 2 #include <cstdlib> 3 #include <string> 4 #include <iostream> 5 #include <cstring> 6 #include <algorithm> 7 #include <cctype> 8 #include <vector> 9 #include <map>10 #include <set>11 #include <iterator>12 #include <functional>13 #include <cmath>14 #include <numeric>15 using namespace std;16 typedef long long LL;17 typedef pair<int,int> PII;18 typedef vector<int> VI;19 #define PB push_back20 #define MP make_pair21 #define SZ size()22 #define CL clear()23 #define AA first24 #define BB second25 #define EPS 1e-826 #define ZERO(x) memset((x),0,sizeof(x))27 const int INF = ~0U>>1;28 const double PI = acos(-1.0);29 30 int get_num(char c){31     if( c==‘_‘ ) return 0;32     if( c==‘.‘) return 27;33     return c-‘a‘+1;34 }35 36 char get_char(int n){37     if( n==0 ) return ‘_‘;38     if( n==27 ) return ‘.‘;39     return n+‘a‘-1;40 }41 42 int main(){43     int k;44     while( scanf("%d",&k),k ){45         char buff[100];46         scanf("%s",buff);47         int plaincode[100],ciphercode[100];48         ZERO(plaincode); ZERO(ciphercode);49         int n = strlen(buff);50         for(int i=0;i<n;i++){51             ciphercode[i] = get_num(buff[i]);52         }53         for(int i=0;i<n;i++){54             plaincode[(k*i)%n] = (ciphercode[i] + i)%28;55         }56         for(int i=0;i<n;i++){57             putchar(get_char(plaincode[i]));58         }59         puts("");60     }61     return 0;62 }