#include <stdio.h>
int main(void){
	int tate, yoko;
	scanf("%d%d",&tate,&yoko);
	
	int count = 0;
	char str[yoko];
	for(int i = 0;i < tate;i ++){
		scanf("%s",str);
		for(int j = 0;j < yoko;j ++){
			if(str[j] != 'R'){
				count++;
			}
		}
	}
	printf("%d",count);
}