#include <stdio.h>
#include <math.h>
#include <string.h>
#include <stdlib.h>

int main(){
    int n, i, counterX=0, counter0=0, obvod, obsah, mozny_obsah, mozny_obvod, counter_stvorcov=0, strana;
    scanf("%d", &n);
    char *pole;
    pole = (char*)malloc(n*sizeof(char));
    scanf("%s", pole);
    for(i=0; i<n; i++){
        if (pole[i] == 'X'){
            counterX++;
        }
        else if (pole[i]=='0'){
            counter0++;
        }
    }

    mozny_obvod = counter0;
    mozny_obsah = counterX;

    strana =mozny_obvod/4+1;

    obvod = (strana-1)*4;
    obsah = (strana-2)*(strana-2);

    while(obsah>=1){
        if (obsah == mozny_obsah){
            counter_stvorcov++;
        }
        obvod -=4;
        obsah = (obvod/4+1)*(obvod/4+1);
    }

    mozny_obvod = counterX;
    mozny_obsah = counter0;

    strana =mozny_obvod/4+1;

    obvod = (strana-1)*4;
    obsah = (strana-2)*(strana-2);

    while(obsah>=1){
        if (obsah == mozny_obsah){
            counter_stvorcov++;
        }
        obvod -=4;
        obsah = (obvod/4+1)*(obvod/4+1);
    }

    printf("%d\n", counter_stvorcov);

    return counter_stvorcov;
}