#include <stdio.h>

int main(void){
    int N;
    scanf("%d", &N);
    char s[N+1];
    scanf("%s", s);
    int countw[N];
    int countb[N];
    int min = N;
    countw[0] = (s[0] == '.');
    countb[0] = (s[0] == '#');
    int count = 0;
    for(int i = 1; i<N; i++){
        countw[i] = countw[i-1] + (s[i] == '.');
        countb[i] = countb[i-1] + (s[i] == '#');
    }
    //iをblack
    if((countb[N-1] == N) || (countw[N-1] == N){
        min = 0;
    }
    for(int i = 1; i<N; i++){
        count = countb[i-1] + (countw[N-1] - countw[i]);
        if(count < min){
            min = count;
        }
    }

    printf("%d\n", min);
    return 0; 
}