#include <stdio.h> #include <string.h> int main() { char str[1000]; while(~scanf("%s",str)) { int n; scanf("%d",&n); int len = strlen(str); int count = 0; int max; int max_index; for(int i =0;i<len-n+1;i++) { for(int j=i;j<i+n;j++) { if(str[j] == 'C'||str[j]=='G') count++; } if(count > max) { max = count; max_index = i; } count = 0; } for(int i = max_index;i<n+max_index;i++) { printf("%c",str[i]); } } }