Expected a ';' error when creating a variable of struct type

Code is given below :

#include <cstdio>
#include <iostream>
#include <deque>

struct vertex {
    bool visited;
    int value;
    int distance;
};

int main() {

    int key_value;
    std::cin >> key_value;

    int num_vertices;
    std::cin >> num_vertices;

    int** matrix;
    matrix = new int*[num_vertices];
    for (int i = 0; i < num_vertices; i++) {
        matrix[i] = new int[num_vertices];
    }

    vertex* vertices;
    vertices = new vertex[num_vertices];

    std::deque<vertex> queue;

    int vertex, value;
    while(std::cin >> vertex >> value) {
        vertices[vertex].value = value;
        int num_edges;
        std::cin >> num_edges;
        for(int i = 0; i < num_edges; i++) {
            int edge_to;
            std::cin >> edge_to;
            matrix[vertex][edge_to] = 1;
        }
    }

    //BFS

    vertices[0].visited = true;
    vertices[0].distance = 0;
    queue.push_back(vertices[0]);

    while(!queue.empty()) {
        vertex cur_v;
        cur_v = queue.front();
        queue.pop_front();
        for(int i = 1; i < num_vertices; i++) {
            if(matrix[cur_v, i]) {
                if(!vertices[i].visited) {
                    vertices[i].visited = true;
                    queue.push_back(vertices[i]);
                }
            }
        }
    }

    return(0);
}

I am getting the following errors,

search_gilene_matt.cc: In function ‘int main()’: search_gilene_matt.cc:42: error: expected ‘;’ before ‘cur_v’ search_gilene_matt.cc:43: error: ‘cur_v’ was not declared in this scope

Can someone shed some light on what would be causing this?

I have looked for a missing semicolon but I don't have any idea of where it would be.