View Compilation Error

0_0_37302156_22277.cpp
0_0_37302156_22277.cpp(12) : error C2065: “stack”: 未声明的标识符
0_0_37302156_22277.cpp(12) : error C2062: 意外的类型“char” 
0_0_37302156_22277.cpp(18) : error C2065: “kh”: 未声明的标识符
0_0_37302156_22277.cpp(18) : error C2228: “.push”的左边必须有类/结构/联合
        类型是“unknown-type”
0_0_37302156_22277.cpp(20) : error C2065: “kh”: 未声明的标识符
0_0_37302156_22277.cpp(20) : error C2228: “.size”的左边必须有类/结构/联合
        类型是“unknown-type”
0_0_37302156_22277.cpp(22) : error C2065: “kh”: 未声明的标识符
0_0_37302156_22277.cpp(22) : error C2228: “.pop”的左边必须有类/结构/联合
        类型是“unknown-type”