Submission #3607216

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Source Code Expand

#include<bits/stdc++.h>
using namespace std;

typedef long long ll;
typedef pair<int, int> P;
typedef tuple<int, int, int> T;

int MOD=1e9+7;
ll INF=1e18;

int dx[]={1, -1, 0, 0};
int dy[]={0, 0, 1, -1};

int main(){
    string s; cin>>s;
    int n=s.size();
    if(n%2==1){
        cout << -1 << endl;
        return 0;
    }
    
    int cnt2=0, ans=0;
    for(int i=0; i<n; i++){
        if(s[i]=='2') cnt2++;
        else cnt2--;
        if(cnt2<0){
            cout << -1 << endl;
            return 0;
        }
        ans=max(ans, cnt2);
    }
    cout << ans << endl;
}

Submission Info

Judge Result