不知道哪里错了，求指导！O(∩_∩)O谢谢~

创建一个栈，将10、12、14入栈，输出栈顶元素，然后退栈，代码如下
#include<iostream.h>
const int size=10;
class stack
{
    int stck[size];
    int tos;
public:
    stack(int tos)
    {tos=0;};
    void push(int ch);
    int pop();
}

void stack::push(int ch)
{
    if(tos==size)
        cout<<"stack is full\n"<<endl;
    stack[tos]=ch;
    tos++;
}

int stack::pop()
{
    if(tos==0)
        cout<<"stack is empty\n"<<endl;
    tos--;
    return stck[tos];
}

void main()
{
    stack s1;
    int i;
    s1.push(10);
    s1.push(12);
    s1.push(14);
    for(i=0;i<3;i++)
        cout<<"stack s1"<<s1.pop()<<"\n";
}

错误如下，，奈何看不懂。。。求指点！！
E:\123\P290 Q5.CPP(14) : error C2628: 'stack' followed by 'void' is illegal (did you forget a ';'?)
E:\123\P290 Q5.CPP(15) : error C2556: 'class stack __thiscall stack::push(int)' : overloaded function differs only by return type from 'void __thiscall stack::push(int)'
        E:\123\P290 Q5.CPP(10) : see declaration of 'push'
E:\123\P290 Q5.CPP(15) : error C2371: 'push' : redefinition; different basic types
        E:\123\P290 Q5.CPP(10) : see declaration of 'push'
E:\123\P290 Q5.CPP(18) : error C2143: syntax error : missing ';' before '['
E:\123\P290 Q5.CPP(18) : error C2143: syntax error : missing ';' before '['
E:\123\P290 Q5.CPP(32) : error C2512: 'stack' : no appropriate default constructor available
E:\123\P290 Q5.CPP(34) : error C2264: 'push' : error in function definition or declaration; function not called
E:\123\P290 Q5.CPP(35) : error C2264: 'push' : error in function definition or declaration; function not called
E:\123\P290 Q5.CPP(36) : error C2264: 'push' : error in function definition or declaration; function not called
Error executing cl.exe.