百练 2767:简单密码

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int main(){
char t[11],A[201];
int i;
while(gets(t)&&strcmp(t,"START")==0){
gets(A);
for( i=0 ; A[i]!='\0' ; i++ ){
if(A[i]>='A'&&A[i]<='E')
A[i] = A[i]+21;
else if(A[i]>='F'&&A[i]<='Z')
A[i] = A[i]-5;
}
if(gets(t)&&strcmp(t,"END")==0)
printf("%s\n",A);
else
break;
}
return 0;
}