if (matrix.size() == 0) return 0;

vector<vector<int> > f;

for (int i = 0; i < matrix.size(); i++) {

vector<int> temp(matrix[i].size());

for (int j = 0; j < matrix[i].size(); j++) {

if (matrix[i][j] == '0') temp[j] = 0; else

if (i == 0) temp[j] = 1; else temp[j] = f[i - 1][j] + 1;

}

f.push_back(temp);

}

vector<vector<int> > left;

for (int i = 0; i < matrix.size(); i++) {

vector<int> temp(matrix[i].size());

stack<int> stk;

for (int j = 0; j < matrix[i].size(); j++) {

while (!stk.empty() && f[i][stk.top()] >= f[i][j]) stk.pop();

if (stk.empty()) temp[j] = -1; else temp[j] = stk.top();

stk.push(j);

}

left.push_back(temp);

}

int area = 0;

for (int i = 0; i < matrix.size(); i++) {

stack<int> stk;

for (int j = matrix[i].size() - 1; j >= 0; j--) {

while (!stk.empty() && f[i][stk.top()] >= f[i][j]) stk.pop();

int right = matrix[i].size();

if (!stk.empty()) right = stk.top();

stk.push(j);

area = max(area, f[i][j] * (right - left[i][j] - 1));

}

}

return area;