#include <stdio.h>

bool has[16000004] = {0};
int val[256];

int v = 0;

int getVal(char c){
	if(val[c] == -1) {
		val[c] = v;
		v++;
	}
	return val[c];
}

int power(int n, int m){
	if(m == 0) return 1;
	int t = power(n, m/2);
	if(m%2 == 0) return t*t;
	return t*t*n;
}

int main() {
	int N,M;
	for(int i = 0; i < 256; i++) val[i] = -1;
	scanf("%d%d\n", &N, &M);
	char *buf = new char[N];
	int pos = 0;
	int ss = 0;
	int w = power(M, N-1);
	for(int i = 0; i < N; i++){
		ss *= M;
		scanf("%c", &buf[i]);
		//printf("%c\n", buf[i]);
		ss += getVal(buf[i]);
	}
	has[ss] = 1;
	int res = 1;
	char temp;
	while(scanf("%c ", &temp) > 0){
		//printf("%c\n", temp);
		ss -= w * getVal(buf[pos]);
		ss *= M;
		ss += getVal(temp);
		buf[pos] = temp;
		if(!has[ss]){
			has[ss] = 1;
			res ++;
		}
		pos += 1;
		pos %= N;
	}
	printf("%d\n", res);
	delete [] buf;
	return 0;
}