http://codeforces.com/contest/332/problem/A
1 #include <cstdio> 2 #include <iostream> 3 #include <cstring> 4 #include <algorithm> 5 #define maxn 3000 6 using namespace std; 7 8 char str[maxn]; 9 10 int main() 11 { 12 int n; 13 cin>>n; 14 cin>>str; 15 int k=strlen(str); 16 int cnt=0; 17 for(int i=n; i<k; i+=n) 18 { 19 if(str[i-1]==str[i-2]&&str[i-3]==str[i-2]) 20 cnt++; 21 } 22 printf("%d\n",cnt); 23 return 0; 24 }