#include <cstdio>
using namespace std;

int N, v[102], x, left, right, prev = 1;

int main(){

scanf("%d", &N);
v[101] = 1;

while(N--){
    scanf("%d", &x);
    v[x] = 1;
}

for(int i = 1; i <= 101; i++){
    if(prev && v[i] == 0){
        left = right = i;
    }
    if(prev == 0 && v[i] == 0){
        right++;
    }
    if(prev == 0 && v[i]){
        printf("%d-%d\n", left, right);
    }prev = v[i];
}

return 0;
}